diff --git a/core/lamp.py b/core/lamp.py
deleted file mode 100644
index 10593d3..0000000
--- a/core/lamp.py
+++ /dev/null
@@ -1,66 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2014 MMD Tools authors
-# This file is part of MMD Tools.
-
-import bpy
-
-from ..bpyutils import FnContext, Props
-
-
-class MMDLamp:
-    def __init__(self, obj):
-        if MMDLamp.isLamp(obj):
-            obj = obj.parent
-        if obj and obj.type == "EMPTY" and obj.mmd_type == "LIGHT":
-            self.__emptyObj = obj
-        else:
-            raise ValueError("%s is not MMDLamp" % str(obj))
-
-    @staticmethod
-    def isLamp(obj):
-        return obj and obj.type in {"LIGHT", "LAMP"}
-
-    @staticmethod
-    def isMMDLamp(obj):
-        if MMDLamp.isLamp(obj):
-            obj = obj.parent
-        return obj and obj.type == "EMPTY" and obj.mmd_type == "LIGHT"
-
-    @staticmethod
-    def convertToMMDLamp(lampObj, scale=1.0):
-        if MMDLamp.isMMDLamp(lampObj):
-            return MMDLamp(lampObj)
-
-        empty = bpy.data.objects.new(name="MMD_Light", object_data=None)
-        FnContext.link_object(FnContext.ensure_context(), empty)
-
-        empty.rotation_mode = "XYZ"
-        empty.lock_rotation = (True, True, True)
-        setattr(empty, Props.empty_display_size, 0.4)
-        empty.scale = [10 * scale] * 3
-        empty.mmd_type = "LIGHT"
-        empty.location = (0, 0, 11 * scale)
-
-        lampObj.parent = empty
-        lampObj.data.color = (0.602, 0.602, 0.602)
-        lampObj.location = (0.5, -0.5, 1.0)
-        lampObj.rotation_mode = "XYZ"
-        lampObj.rotation_euler = (0, 0, 0)
-        lampObj.lock_rotation = (True, True, True)
-
-        constraint = lampObj.constraints.new(type="TRACK_TO")
-        constraint.name = "mmd_lamp_track"
-        constraint.target = empty
-        constraint.track_axis = "TRACK_NEGATIVE_Z"
-        constraint.up_axis = "UP_Y"
-
-        return MMDLamp(empty)
-
-    def object(self):
-        return self.__emptyObj
-
-    def lamp(self):
-        for i in self.__emptyObj.children:
-            if MMDLamp.isLamp(i):
-                return i
-        raise KeyError
diff --git a/core/mmd/bpyutils.py b/core/mmd/bpyutils.py
index c5c9d76..3bc6d28 100644
--- a/core/mmd/bpyutils.py
+++ b/core/mmd/bpyutils.py
@@ -6,9 +6,13 @@
 # MMD Tools is licensed under the terms of the GNU General Public License version 3 (GPLv3) same as Avatar Toolkit.
 
 import contextlib
-from typing import Generator, List, Optional, TypeVar
+from typing import Generator, List, Optional, TypeVar, Any, Set, Tuple, Dict, Union
 
 import bpy
+from bpy.types import Object, Context, ID, Key, ShapeKey, FCurve, LayerCollection, Collection
+from bpy.types import AddonPreferences, Addon, WindowManager, Area, Region, Window
+
+from ..logging_setup import logger
 
 
 class Props:  # For API changes of only name changed properties
@@ -20,7 +24,7 @@ class Props:  # For API changes of only name changed properties
 
 
 class __EditMode:
-    def __init__(self, obj):
+    def __init__(self, obj: Object):
         if not isinstance(obj, bpy.types.Object):
             raise ValueError
         self.__prevMode = obj.mode
@@ -30,10 +34,10 @@ class __EditMode:
             if obj.mode != "EDIT":
                 bpy.ops.object.mode_set(mode="EDIT")
 
-    def __enter__(self):
+    def __enter__(self) -> Any:
         return self.__obj.data
 
-    def __exit__(self, type, value, traceback):
+    def __exit__(self, type: Any, value: Any, traceback: Any) -> None:
         if self.__prevMode == "EDIT":
             bpy.ops.object.mode_set(mode="OBJECT")  # update edited data
         bpy.ops.object.mode_set(mode=self.__prevMode)
@@ -41,17 +45,18 @@ class __EditMode:
 
 
 class __SelectObjects:
-    def __init__(self, active_object: bpy.types.Object, selected_objects: Optional[List[bpy.types.Object]] = None):
+    def __init__(self, active_object: Object, selected_objects: Optional[List[Object]] = None):
         if not isinstance(active_object, bpy.types.Object):
             raise ValueError
         try:
             bpy.ops.object.mode_set(mode="OBJECT")
         except Exception:
+            logger.debug("Failed to set object mode")
             pass
 
-        contenxt = FnContext.ensure_context()
+        context = FnContext.ensure_context()
 
-        for i in contenxt.selected_objects:
+        for i in context.selected_objects:
             i.select_set(False)
 
         self.__active_object = active_object
@@ -60,23 +65,23 @@ class __SelectObjects:
         self.__hides: List[bool] = []
         for i in self.__selected_objects:
             self.__hides.append(i.hide_get())
-            FnContext.select_object(contenxt, i)
-        FnContext.set_active_object(contenxt, active_object)
+            FnContext.select_object(context, i)
+        FnContext.set_active_object(context, active_object)
 
-    def __enter__(self) -> bpy.types.Object:
+    def __enter__(self) -> Object:
         return self.__active_object
 
-    def __exit__(self, type, value, traceback):
+    def __exit__(self, type: Any, value: Any, traceback: Any) -> None:
         for i, j in zip(self.__selected_objects, self.__hides):
             i.hide_set(j)
 
 
-def setParent(obj, parent):
+def setParent(obj: Object, parent: Object) -> None:
     with select_object(parent, objects=[parent, obj]):
         bpy.ops.object.parent_set(type="OBJECT", xmirror=False, keep_transform=False)
 
 
-def setParentToBone(obj, parent, bone_name):
+def setParentToBone(obj: Object, parent: Object, bone_name: str) -> None:
     with select_object(parent, objects=[parent, obj]):
         bpy.ops.object.mode_set(mode="POSE")
         parent.data.bones.active = parent.data.bones[bone_name]
@@ -84,7 +89,7 @@ def setParentToBone(obj, parent, bone_name):
         bpy.ops.object.mode_set(mode="OBJECT")
 
 
-def edit_object(obj):
+def edit_object(obj: Object) -> __EditMode:
     """Set the object interaction mode to 'EDIT'
 
     It is recommended to use 'edit_object' with 'with' statement like the following code.
@@ -95,7 +100,7 @@ def edit_object(obj):
     return __EditMode(obj)
 
 
-def select_object(obj: bpy.types.Object, objects: Optional[List[bpy.types.Object]] = None):
+def select_object(obj: Object, objects: Optional[List[Object]] = None) -> __SelectObjects:
     """Select objects.
 
     It is recommended to use 'select_object' with 'with' statement like the following code.
@@ -108,20 +113,23 @@ def select_object(obj: bpy.types.Object, objects: Optional[List[bpy.types.Object
     return __SelectObjects(obj, objects)
 
 
-def duplicateObject(obj, total_len):
+def duplicateObject(obj: Object, total_len: int) -> List[Object]:
     return FnContext.duplicate_object(FnContext.ensure_context(), obj, total_len)
 
 
-def createObject(name="Object", object_data=None, target_scene=None):
+def createObject(name: str = "Object", object_data: Optional[ID] = None, target_scene: Optional[bpy.types.Scene] = None) -> Object:
     context = FnContext.ensure_context(target_scene)
     return FnContext.set_active_object(context, FnContext.new_and_link_object(context, name, object_data))
 
 
-def makeSphere(segment=8, ring_count=5, radius=1.0, target_object=None):
+def makeSphere(segment: int = 8, ring_count: int = 5, radius: float = 1.0, target_object: Optional[Object] = None) -> Object:
     import bmesh
 
     if target_object is None:
         target_object = createObject(name="Sphere")
+        logger.debug(f"Created new sphere object: {target_object.name}")
+    else:
+        logger.debug(f"Using existing object for sphere: {target_object.name}")
 
     mesh = target_object.data
     bm = bmesh.new()
@@ -138,12 +146,15 @@ def makeSphere(segment=8, ring_count=5, radius=1.0, target_object=None):
     return target_object
 
 
-def makeBox(size=(1, 1, 1), target_object=None):
+def makeBox(size: Tuple[float, float, float] = (1, 1, 1), target_object: Optional[Object] = None) -> Object:
     import bmesh
     from mathutils import Matrix
 
     if target_object is None:
         target_object = createObject(name="Box")
+        logger.debug(f"Created new box object: {target_object.name}")
+    else:
+        logger.debug(f"Using existing object for box: {target_object.name}")
 
     mesh = target_object.data
     bm = bmesh.new()
@@ -159,13 +170,16 @@ def makeBox(size=(1, 1, 1), target_object=None):
     return target_object
 
 
-def makeCapsule(segment=8, ring_count=2, radius=1.0, height=1.0, target_object=None):
+def makeCapsule(segment: int = 8, ring_count: int = 2, radius: float = 1.0, height: float = 1.0, target_object: Optional[Object] = None) -> Object:
     import math
-
     import bmesh
 
     if target_object is None:
         target_object = createObject(name="Capsule")
+        logger.debug(f"Created new capsule object: {target_object.name}")
+    else:
+        logger.debug(f"Using existing object for capsule: {target_object.name}")
+        
     height = max(height, 1e-3)
 
     mesh = target_object.data
@@ -224,10 +238,10 @@ def makeCapsule(segment=8, ring_count=2, radius=1.0, height=1.0, target_object=N
 
 
 class TransformConstraintOp:
-    __MIN_MAX_MAP = {"ROTATION": "_rot", "SCALE": "_scale"}
+    __MIN_MAX_MAP: Dict[Union[str, Tuple[str, str]], Union[str, Tuple[str, ...]]] = {"ROTATION": "_rot", "SCALE": "_scale"}
 
     @staticmethod
-    def create(constraints, name, map_type):
+    def create(constraints: bpy.types.ObjectConstraints, name: str, map_type: str) -> bpy.types.TransformConstraint:
         c = constraints.get(name, None)
         if c and c.type != "TRANSFORM":
             constraints.remove(c)
@@ -245,7 +259,7 @@ class TransformConstraintOp:
         return c
 
     @classmethod
-    def min_max_attributes(cls, map_type, name_id=""):
+    def min_max_attributes(cls, map_type: str, name_id: str = "") -> Tuple[str, ...]:
         key = (map_type, name_id)
         ret = cls.__MIN_MAX_MAP.get(key, None)
         if ret is None:
@@ -255,7 +269,7 @@ class TransformConstraintOp:
         return ret
 
     @classmethod
-    def update_min_max(cls, constraint, value, influence=1):
+    def update_min_max(cls, constraint: bpy.types.TransformConstraint, value: float, influence: Optional[float] = 1) -> None:
         c = constraint
         if not c or c.type != "TRANSFORM":
             return
@@ -279,14 +293,14 @@ class FnObject:
         raise NotImplementedError("This class is not expected to be instantiated.")
 
     @staticmethod
-    def mesh_remove_shape_key(mesh_object: bpy.types.Object, shape_key: bpy.types.ShapeKey):
+    def mesh_remove_shape_key(mesh_object: Object, shape_key: ShapeKey) -> None:
         assert isinstance(mesh_object.data, bpy.types.Mesh)
 
-        key: bpy.types.Key = shape_key.id_data
+        key: Key = shape_key.id_data
         assert key == mesh_object.data.shape_keys
 
         if mesh_object.animation_data is not None:
-            fc_curve: bpy.types.FCurve
+            fc_curve: FCurve
             for fc_curve in mesh_object.animation_data.drivers:
                 if not fc_curve.data_path.startswith(shape_key.path_from_id()):
                     continue
@@ -310,35 +324,35 @@ class FnContext:
         raise NotImplementedError("This class is not expected to be instantiated.")
 
     @staticmethod
-    def ensure_context(context: Optional[bpy.types.Context] = None) -> bpy.types.Context:
+    def ensure_context(context: Optional[Context] = None) -> Context:
         return context or bpy.context
 
     @staticmethod
-    def get_active_object(context: bpy.types.Context) -> Optional[bpy.types.Object]:
+    def get_active_object(context: Context) -> Optional[Object]:
         return context.active_object
 
     @staticmethod
-    def set_active_object(context: bpy.types.Context, obj: bpy.types.Object) -> bpy.types.Object:
+    def set_active_object(context: Context, obj: Object) -> Object:
         context.view_layer.objects.active = obj
         return obj
 
     @staticmethod
-    def set_active_and_select_single_object(context: bpy.types.Context, obj: bpy.types.Object) -> bpy.types.Object:
+    def set_active_and_select_single_object(context: Context, obj: Object) -> Object:
         return FnContext.set_active_object(context, FnContext.select_single_object(context, obj))
 
     @staticmethod
-    def get_scene_objects(context: bpy.types.Context) -> bpy.types.SceneObjects:
+    def get_scene_objects(context: Context) -> bpy.types.SceneObjects:
         return context.scene.objects
 
     @staticmethod
-    def ensure_selectable(context: bpy.types.Context, obj: bpy.types.Object) -> bpy.types.Object:
+    def ensure_selectable(context: Context, obj: Object) -> Object:
         obj.hide_viewport = False
         obj.hide_select = False
         obj.hide_set(False)
 
         if obj not in context.selectable_objects:
 
-            def __layer_check(layer_collection: bpy.types.LayerCollection) -> bool:
+            def __layer_check(layer_collection: LayerCollection) -> bool:
                 for lc in layer_collection.children:
                     if __layer_check(lc):
                         lc.hide_viewport = False
@@ -360,44 +374,44 @@ class FnContext:
         return obj
 
     @staticmethod
-    def select_object(context: bpy.types.Context, obj: bpy.types.Object) -> bpy.types.Object:
+    def select_object(context: Context, obj: Object) -> Object:
         FnContext.ensure_selectable(context, obj).select_set(True)
         return obj
 
     @staticmethod
-    def select_objects(context: bpy.types.Context, *objects: bpy.types.Object) -> List[bpy.types.Object]:
+    def select_objects(context: Context, *objects: Object) -> List[Object]:
         return [FnContext.select_object(context, obj) for obj in objects]
 
     @staticmethod
-    def select_single_object(context: bpy.types.Context, obj: bpy.types.Object) -> bpy.types.Object:
+    def select_single_object(context: Context, obj: Object) -> Object:
         for i in context.selected_objects:
             if i != obj:
                 i.select_set(False)
         return FnContext.select_object(context, obj)
 
     @staticmethod
-    def link_object(context: bpy.types.Context, obj: bpy.types.Object) -> bpy.types.Object:
+    def link_object(context: Context, obj: Object) -> Object:
         context.collection.objects.link(obj)
         return obj
 
     @staticmethod
-    def new_and_link_object(context: bpy.types.Context, name: str, object_data: Optional[bpy.types.ID]) -> bpy.types.Object:
+    def new_and_link_object(context: Context, name: str, object_data: Optional[ID]) -> Object:
         return FnContext.link_object(context, bpy.data.objects.new(name=name, object_data=object_data))
 
     @staticmethod
-    def duplicate_object(context: bpy.types.Context, object_to_duplicate: bpy.types.Object, target_count: int) -> List[bpy.types.Object]:
+    def duplicate_object(context: Context, object_to_duplicate: Object, target_count: int) -> List[Object]:
         """
         Duplicate object.
 
         This function duplicates the given object and returns a list of duplicated objects.
 
         Args:
-            context (bpy.types.Context): The context in which the duplication is performed.
-            object_to_duplicate (bpy.types.Object): The object to be duplicated.
+            context (Context): The context in which the duplication is performed.
+            object_to_duplicate (Object): The object to be duplicated.
             target_count (int): The desired count of duplicated objects.
 
         Returns:
-            List[bpy.types.Object]: A list of duplicated objects.
+            List[Object]: A list of duplicated objects.
 
         Raises:
             AssertionError: If the number of selected objects in the context is not equal to 1 or if the selected object is not the same as the object to be duplicated.
@@ -421,27 +435,28 @@ class FnContext:
                     last_selected_objects[i].select_set(True)
                 last_selected_objects = context.selected_objects
         assert len(result_objects) == target_count
+        logger.debug(f"Duplicated object {object_to_duplicate.name} to create {target_count} objects")
         return result_objects
 
     @staticmethod
-    def find_user_layer_collection_by_object(context: bpy.types.Context, target_object: bpy.types.Object) -> Optional[bpy.types.LayerCollection]:
+    def find_user_layer_collection_by_object(context: Context, target_object: Object) -> Optional[LayerCollection]:
         """
         Finds the layer collection that contains the given target_object in the user's collections.
 
         Args:
-            context (bpy.types.Context): The Blender context.
-            target_object (bpy.types.Object): The target object to find the layer collection for.
+            context (Context): The Blender context.
+            target_object (Object): The target object to find the layer collection for.
 
         Returns:
-            Optional[bpy.types.LayerCollection]: The layer collection that contains the target_object, or None if not found.
+            Optional[LayerCollection]: The layer collection that contains the target_object, or None if not found.
         """
-        scene_layer_collection: bpy.types.LayerCollection = context.view_layer.layer_collection
+        scene_layer_collection: LayerCollection = context.view_layer.layer_collection
 
-        def find_layer_collection_by_name(layer_collection: bpy.types.LayerCollection, name: str) -> Optional[bpy.types.LayerCollection]:
+        def find_layer_collection_by_name(layer_collection: LayerCollection, name: str) -> Optional[LayerCollection]:
             if layer_collection.name == name:
                 return layer_collection
 
-            child_layer_collection: bpy.types.LayerCollection
+            child_layer_collection: LayerCollection
             for child_layer_collection in layer_collection.children:
                 found = find_layer_collection_by_name(child_layer_collection, name)
                 if found is not None:
@@ -449,7 +464,7 @@ class FnContext:
 
             return None
 
-        user_collection: bpy.types.Collection
+        user_collection: Collection
         for user_collection in target_object.users_collection:
             found = find_layer_collection_by_name(scene_layer_collection, user_collection.name)
             if found is not None:
@@ -459,7 +474,7 @@ class FnContext:
 
     @staticmethod
     @contextlib.contextmanager
-    def temp_override_active_layer_collection(context: bpy.types.Context, target_object: bpy.types.Object) -> Generator[bpy.types.Context, None, None]:
+    def temp_override_active_layer_collection(context: Context, target_object: Object) -> Generator[Context, None, None]:
         """
         Context manager to temporarily override the active_layer_collection that contains the target object.
 
@@ -467,11 +482,11 @@ class FnContext:
         It ensures that the original active_layer_collection is restored after the context is exited.
 
         Args:
-            context (bpy.types.Context): The context in which the active_layer_collection will be overridden.
-            target_object (bpy.types.Object): The target object whose layer collection will be set as the active_layer_collection.
+            context (Context): The context in which the active_layer_collection will be overridden.
+            target_object (Object): The target object whose layer collection will be set as the active_layer_collection.
 
         Yields:
-            bpy.types.Context: The modified context with the active_layer_collection overridden.
+            Context: The modified context with the active_layer_collection overridden.
 
         Example:
             with FnContext.temp_override_active_layer_collection(context, target_object):
@@ -492,24 +507,24 @@ class FnContext:
                 context.view_layer.active_layer_collection = original_layer_collection
 
     @staticmethod
-    def __get_addon_preferences(context: bpy.types.Context) -> Optional[bpy.types.AddonPreferences]:
-        addon: bpy.types.Addon = context.preferences.addons.get(__package__, None)
+    def __get_addon_preferences(context: Context) -> Optional[AddonPreferences]:
+        addon: Addon = context.preferences.addons.get(__package__, None)
         return addon.preferences if addon else None
 
     @staticmethod
-    def get_addon_preferences_attribute(context: bpy.types.Context, attribute_name: str, default_value: ADDON_PREFERENCE_ATTRIBUTE_VALUE_TYPE = None) -> ADDON_PREFERENCE_ATTRIBUTE_VALUE_TYPE:
+    def get_addon_preferences_attribute(context: Context, attribute_name: str, default_value: ADDON_PREFERENCE_ATTRIBUTE_VALUE_TYPE = None) -> ADDON_PREFERENCE_ATTRIBUTE_VALUE_TYPE:
         return getattr(FnContext.__get_addon_preferences(context), attribute_name, default_value)
 
     @staticmethod
     def temp_override_objects(
-        context: bpy.types.Context,
-        window: Optional[bpy.types.Window] = None,
-        area: Optional[bpy.types.Area] = None,
-        region: Optional[bpy.types.Region] = None,
-        active_object: Optional[bpy.types.Object] = None,
-        selected_objects: Optional[List[bpy.types.Object]] = None,
-        **keywords,
-    ) -> Generator[bpy.types.Context, None, None]:
+        context: Context,
+        window: Optional[Window] = None,
+        area: Optional[Area] = None,
+        region: Optional[Region] = None,
+        active_object: Optional[Object] = None,
+        selected_objects: Optional[List[Object]] = None,
+        **keywords: Any,
+    ) -> Generator[Context, None, None]:
         if active_object is not None:
             keywords["active_object"] = active_object
             keywords["object"] = active_object
diff --git a/core/mmd/cycles_converter.py b/core/mmd/cycles_converter.py
index 2a8e531..5f10140 100644
--- a/core/mmd/cycles_converter.py
+++ b/core/mmd/cycles_converter.py
@@ -5,39 +5,44 @@
 # Neoneko has modified this file to work with Avatar Toolkit and may of made changes or improvements.
 # MMD Tools is licensed under the terms of the GNU General Public License version 3 (GPLv3) same as Avatar Toolkit.
 
-from typing import Iterable, Optional
+from typing import Iterable, Optional, Any, List, Tuple, Union
 
 import bpy
+from bpy.types import Material, NodeTree, Node, NodeSocket, ShaderNodeGroup, ShaderNodeOutputMaterial, NodeLink
 
+from ..logging_setup import logger
 from .core.shader import _NodeGroupUtils
 from .core.material import FnMaterial
 
 
-def __switchToCyclesRenderEngine():
+def __switchToCyclesRenderEngine() -> None:
     if bpy.context.scene.render.engine != "CYCLES":
+        logger.debug("Switching render engine to Cycles")
         bpy.context.scene.render.engine = "CYCLES"
 
 
-def __exposeNodeTreeInput(in_socket, name, default_value, node_input, shader):
+def __exposeNodeTreeInput(in_socket: NodeSocket, name: str, default_value: Any, node_input: Node, shader: NodeTree) -> None:
     _NodeGroupUtils(shader).new_input_socket(name, in_socket, default_value)
 
 
-def __exposeNodeTreeOutput(out_socket, name, node_output, shader):
+def __exposeNodeTreeOutput(out_socket: NodeSocket, name: str, node_output: Node, shader: NodeTree) -> None:
     _NodeGroupUtils(shader).new_output_socket(name, out_socket)
 
 
-def __getMaterialOutput(nodes, bl_idname):
+def __getMaterialOutput(nodes: bpy.types.Nodes, bl_idname: str) -> Node:
     o = next((n for n in nodes if n.bl_idname == bl_idname and n.is_active_output), None) or nodes.new(bl_idname)
     o.is_active_output = True
     return o
 
 
-def create_MMDAlphaShader():
+def create_MMDAlphaShader() -> NodeTree:
     __switchToCyclesRenderEngine()
 
     if "MMDAlphaShader" in bpy.data.node_groups:
+        logger.debug("Using existing MMDAlphaShader node group")
         return bpy.data.node_groups["MMDAlphaShader"]
 
+    logger.info("Creating new MMDAlphaShader node group")
     shader = bpy.data.node_groups.new(name="MMDAlphaShader", type="ShaderNodeTree")
 
     node_input = shader.nodes.new("NodeGroupInput")
@@ -59,26 +64,28 @@ def create_MMDAlphaShader():
     return shader
 
 
-def create_MMDBasicShader():
+def create_MMDBasicShader() -> NodeTree:
     __switchToCyclesRenderEngine()
 
     if "MMDBasicShader" in bpy.data.node_groups:
+        logger.debug("Using existing MMDBasicShader node group")
         return bpy.data.node_groups["MMDBasicShader"]
 
-    shader: bpy.types.ShaderNodeTree = bpy.data.node_groups.new(name="MMDBasicShader", type="ShaderNodeTree")
+    logger.info("Creating new MMDBasicShader node group")
+    shader: NodeTree = bpy.data.node_groups.new(name="MMDBasicShader", type="ShaderNodeTree")
 
-    node_input: bpy.types.NodeGroupInput = shader.nodes.new("NodeGroupInput")
-    node_output: bpy.types.NodeGroupOutput = shader.nodes.new("NodeGroupOutput")
+    node_input: Node = shader.nodes.new("NodeGroupInput")
+    node_output: Node = shader.nodes.new("NodeGroupOutput")
     node_output.location.x += 250
     node_input.location.x -= 500
 
-    dif: bpy.types.ShaderNodeBsdfDiffuse = shader.nodes.new("ShaderNodeBsdfDiffuse")
+    dif: Node = shader.nodes.new("ShaderNodeBsdfDiffuse")
     dif.location.x -= 250
     dif.location.y += 150
-    glo: bpy.types.ShaderNodeBsdfAnisotropic = shader.nodes.new("ShaderNodeBsdfAnisotropic")
+    glo: Node = shader.nodes.new("ShaderNodeBsdfAnisotropic")
     glo.location.x -= 250
     glo.location.y -= 150
-    mix: bpy.types.ShaderNodeMixShader = shader.nodes.new("ShaderNodeMixShader")
+    mix: Node = shader.nodes.new("ShaderNodeMixShader")
     shader.links.new(mix.inputs[1], dif.outputs["BSDF"])
     shader.links.new(mix.inputs[2], glo.outputs["BSDF"])
 
@@ -91,7 +98,7 @@ def create_MMDBasicShader():
     return shader
 
 
-def __enum_linked_nodes(node: bpy.types.Node) -> Iterable[bpy.types.Node]:
+def __enum_linked_nodes(node: Node) -> Iterable[Node]:
     yield node
     if node.parent:
         yield node.parent
@@ -99,7 +106,8 @@ def __enum_linked_nodes(node: bpy.types.Node) -> Iterable[bpy.types.Node]:
         yield from __enum_linked_nodes(n)
 
 
-def __cleanNodeTree(material: bpy.types.Material):
+def __cleanNodeTree(material: Material) -> None:
+    logger.debug(f"Cleaning node tree for material: {material.name}")
     nodes = material.node_tree.nodes
     node_names = set(n.name for n in nodes)
     for o in (n for n in nodes if n.bl_idname in {"ShaderNodeOutput", "ShaderNodeOutputMaterial"}):
@@ -109,40 +117,46 @@ def __cleanNodeTree(material: bpy.types.Material):
         nodes.remove(nodes[name])
 
 
-def convertToCyclesShader(obj: bpy.types.Object, use_principled=False, clean_nodes=False, subsurface=0.001):
+def convertToCyclesShader(obj: bpy.types.Object, use_principled: bool = False, clean_nodes: bool = False, subsurface: float = 0.001) -> None:
+    logger.info(f"Converting {obj.name} to Cycles shader (use_principled={use_principled}, clean_nodes={clean_nodes})")
     __switchToCyclesRenderEngine()
     convertToBlenderShader(obj, use_principled, clean_nodes, subsurface)
 
 
-def convertToBlenderShader(obj: bpy.types.Object, use_principled=False, clean_nodes=False, subsurface=0.001):
+def convertToBlenderShader(obj: bpy.types.Object, use_principled: bool = False, clean_nodes: bool = False, subsurface: float = 0.001) -> None:
     for i in obj.material_slots:
         if not i.material:
             continue
         if not i.material.use_nodes:
+            logger.debug(f"Enabling nodes for material: {i.material.name}")
             i.material.use_nodes = True
             __convertToMMDBasicShader(i.material)
         if use_principled:
+            logger.debug(f"Converting material to Principled BSDF: {i.material.name}")
             __convertToPrincipledBsdf(i.material, subsurface)
         if clean_nodes:
             __cleanNodeTree(i.material)
 
-def convertToMMDShader(obj):
+def convertToMMDShader(obj: bpy.types.Object) -> None:
     """BSDF -> MMDShaderDev conversion."""
+    logger.info(f"Converting {obj.name} to MMD shader")
     for i in obj.material_slots:
         if not i.material:
             continue
         if not i.material.use_nodes:
+            logger.debug(f"Enabling nodes for material: {i.material.name}")
             i.material.use_nodes = True
         FnMaterial.convert_to_mmd_material(i.material)
 
-def __convertToMMDBasicShader(material: bpy.types.Material):
+def __convertToMMDBasicShader(material: Material) -> None:
+    logger.debug(f"Converting material to MMD Basic Shader: {material.name}")
     # TODO: test me
     mmd_basic_shader_grp = create_MMDBasicShader()
     mmd_alpha_shader_grp = create_MMDAlphaShader()
 
-    if not any(filter(lambda x: isinstance(x, bpy.types.ShaderNodeGroup) and x.node_tree.name in {"MMDBasicShader", "MMDAlphaShader"}, material.node_tree.nodes)):
+    if not any(filter(lambda x: isinstance(x, ShaderNodeGroup) and x.node_tree.name in {"MMDBasicShader", "MMDAlphaShader"}, material.node_tree.nodes)):
         # Add nodes for Cycles Render
-        shader: bpy.types.ShaderNodeGroup = material.node_tree.nodes.new("ShaderNodeGroup")
+        shader: ShaderNodeGroup = material.node_tree.nodes.new("ShaderNodeGroup")
         shader.node_tree = mmd_basic_shader_grp
         shader.inputs[0].default_value[:3] = material.diffuse_color[:3]
         shader.inputs[1].default_value[:3] = material.specular_color[:3]
@@ -157,7 +171,8 @@ def __convertToMMDBasicShader(material: bpy.types.Material):
             alpha_value = material.diffuse_color[3]
 
         if alpha_value < 1.0:
-            alpha_shader: bpy.types.ShaderNodeGroup = material.node_tree.nodes.new("ShaderNodeGroup")
+            logger.debug(f"Material has alpha: {material.name}, alpha={alpha_value}")
+            alpha_shader: ShaderNodeGroup = material.node_tree.nodes.new("ShaderNodeGroup")
             alpha_shader.location.x = shader.location.x + 250
             alpha_shader.location.y = shader.location.y - 150
             alpha_shader.node_tree = mmd_alpha_shader_grp
@@ -165,21 +180,22 @@ def __convertToMMDBasicShader(material: bpy.types.Material):
             material.node_tree.links.new(alpha_shader.inputs[0], outplug)
             outplug = alpha_shader.outputs[0]
 
-        material_output: bpy.types.ShaderNodeOutputMaterial = __getMaterialOutput(material.node_tree.nodes, "ShaderNodeOutputMaterial")
+        material_output: ShaderNodeOutputMaterial = __getMaterialOutput(material.node_tree.nodes, "ShaderNodeOutputMaterial")
         material.node_tree.links.new(material_output.inputs["Surface"], outplug)
         material_output.location.x = shader.location.x + 500
         material_output.location.y = shader.location.y - 150
 
 
-def __convertToPrincipledBsdf(material: bpy.types.Material, subsurface: float):
+def __convertToPrincipledBsdf(material: Material, subsurface: float) -> None:
+    logger.debug(f"Converting material to Principled BSDF: {material.name}")
     node_names = set()
-    for s in (n for n in material.node_tree.nodes if isinstance(n, bpy.types.ShaderNodeGroup)):
+    for s in (n for n in material.node_tree.nodes if isinstance(n, ShaderNodeGroup)):
         if s.node_tree.name == "MMDBasicShader":
-            l: bpy.types.NodeLink
+            l: NodeLink
             for l in s.outputs[0].links:
                 to_node = l.to_node
                 # assuming there is no bpy.types.NodeReroute between MMDBasicShader and MMDAlphaShader
-                if isinstance(to_node, bpy.types.ShaderNodeGroup) and to_node.node_tree.name == "MMDAlphaShader":
+                if isinstance(to_node, ShaderNodeGroup) and to_node.node_tree.name == "MMDAlphaShader":
                     __switchToPrincipledBsdf(material.node_tree, s, subsurface, node_alpha=to_node)
                     node_names.add(to_node.name)
                 else:
@@ -194,8 +210,9 @@ def __convertToPrincipledBsdf(material: bpy.types.Material, subsurface: float):
         nodes.remove(nodes[name])
 
 
-def __switchToPrincipledBsdf(node_tree: bpy.types.NodeTree, node_basic: bpy.types.ShaderNodeGroup, subsurface: float, node_alpha: Optional[bpy.types.ShaderNodeGroup] = None):
-    shader: bpy.types.ShaderNodeBsdfPrincipled = node_tree.nodes.new("ShaderNodeBsdfPrincipled")
+def __switchToPrincipledBsdf(node_tree: NodeTree, node_basic: ShaderNodeGroup, subsurface: float, node_alpha: Optional[ShaderNodeGroup] = None) -> None:
+    logger.debug(f"Switching to Principled BSDF: {node_basic.name}")
+    shader: Node = node_tree.nodes.new("ShaderNodeBsdfPrincipled")
     shader.parent = node_basic.parent
     shader.location.x = node_basic.location.x
     shader.location.y = node_basic.location.y
diff --git a/core/mmd/utils.py b/core/mmd/utils.py
index c4006ac..6d6f731 100644
--- a/core/mmd/utils.py
+++ b/core/mmd/utils.py
@@ -5,18 +5,19 @@
 # Neoneko has modified this file to work with Avatar Toolkit and may of made changes or improvements.
 # MMD Tools is licensed under the terms of the GNU General Public License version 3 (GPLv3) same as Avatar Toolkit.
 
-import logging
 import os
 import re
-from typing import Callable, Optional, Set
+from typing import Callable, Dict, List, Optional, Set, Tuple, Union, Any
 
 import bpy
+from bpy.types import Object, Bone, PoseBone, Mesh, VertexGroup
 
+from ..logging_setup import logger
 from .bpyutils import FnContext
 
 
 ## 指定したオブジェクトのみを選択状態かつアクティブにする
-def selectAObject(obj):
+def selectAObject(obj: Object) -> None:
     try:
         bpy.ops.object.mode_set(mode="OBJECT")
     except Exception:
@@ -27,13 +28,13 @@ def selectAObject(obj):
 
 
 ## 現在のモードを指定したオブジェクトのEdit Modeに変更する
-def enterEditMode(obj):
+def enterEditMode(obj: Object) -> None:
     selectAObject(obj)
     if obj.mode != "EDIT":
         bpy.ops.object.mode_set(mode="EDIT")
 
 
-def setParentToBone(obj, parent, bone_name):
+def setParentToBone(obj: Object, parent: Object, bone_name: str) -> None:
     selectAObject(obj)
     FnContext.set_active_object(FnContext.ensure_context(), parent)
     bpy.ops.object.mode_set(mode="POSE")
@@ -42,7 +43,7 @@ def setParentToBone(obj, parent, bone_name):
     bpy.ops.object.mode_set(mode="OBJECT")
 
 
-def selectSingleBone(context, armature, bone_name, reset_pose=False):
+def selectSingleBone(context: bpy.types.Context, armature: Object, bone_name: str, reset_pose: bool = False) -> None:
     try:
         bpy.ops.object.mode_set(mode="OBJECT")
     except:
@@ -55,7 +56,7 @@ def selectSingleBone(context, armature, bone_name, reset_pose=False):
         for p_bone in armature.pose.bones:
             p_bone.matrix_basis.identity()
     armature_bones: bpy.types.ArmatureBones = armature.data.bones
-    i: bpy.types.Bone
+    i: Bone
     for i in armature_bones:
         i.select = i.name == bone_name
         i.select_head = i.select_tail = i.select
@@ -69,7 +70,7 @@ __CONVERT_NAME_TO_R_REGEXP = re.compile("^(.*)右(.*)$")
 
 
 ## 日本語で左右を命名されている名前をblender方式のL(R)に変更する
-def convertNameToLR(name, use_underscore=False):
+def convertNameToLR(name: str, use_underscore: bool = False) -> str:
     m = __CONVERT_NAME_TO_L_REGEXP.match(name)
     delimiter = "_" if use_underscore else "."
     if m:
@@ -84,7 +85,7 @@ __CONVERT_L_TO_NAME_REGEXP = re.compile(r"(?P<lr>(?P<separator>[._])[lL])(?P<aft
 __CONVERT_R_TO_NAME_REGEXP = re.compile(r"(?P<lr>(?P<separator>[._])[rR])(?P<after>($|(?P=separator)))")
 
 
-def convertLRToName(name):
+def convertLRToName(name: str) -> str:
     match = __CONVERT_L_TO_NAME_REGEXP.search(name)
     if match:
         return f"左{name[0:match.start()]}{match['after']}{name[match.end():]}"
@@ -97,7 +98,7 @@ def convertLRToName(name):
 
 
 ## src_vertex_groupのWeightをdest_vertex_groupにaddする
-def mergeVertexGroup(meshObj, src_vertex_group_name, dest_vertex_group_name):
+def mergeVertexGroup(meshObj: Object, src_vertex_group_name: str, dest_vertex_group_name: str) -> None:
     mesh = meshObj.data
     src_vertex_group = meshObj.vertex_groups[src_vertex_group_name]
     dest_vertex_group = meshObj.vertex_groups[dest_vertex_group_name]
@@ -111,7 +112,7 @@ def mergeVertexGroup(meshObj, src_vertex_group_name, dest_vertex_group_name):
             pass
 
 
-def separateByMaterials(meshObj: bpy.types.Object):
+def separateByMaterials(meshObj: Object) -> None:
     if len(meshObj.data.materials) < 2:
         selectAObject(meshObj)
         return
@@ -134,7 +135,7 @@ def separateByMaterials(meshObj: bpy.types.Object):
     bpy.data.objects.remove(dummy_parent)
 
 
-def clearUnusedMeshes():
+def clearUnusedMeshes() -> None:
     meshes_to_delete = []
     for mesh in bpy.data.meshes:
         if mesh.users == 0:
@@ -146,7 +147,7 @@ def clearUnusedMeshes():
 
 ## Boneのカスタムプロパティにname_jが存在する場合、name_jの値を
 # それ以外の場合は通常のbone名をキーとしたpose_boneへの辞書を作成
-def makePmxBoneMap(armObj):
+def makePmxBoneMap(armObj: Object) -> Dict[str, PoseBone]:
     # Maintain backward compatibility with mmd_tools v0.4.x or older.
     return {(i.mmd_bone.name_j or i.get("mmd_bone_name_j", i.get("name_j", i.name))): i for i in armObj.pose.bones}
 
@@ -175,7 +176,7 @@ def unique_name(name: str, used_names: Set[str]) -> str:
     return new_name
 
 
-def int2base(x, base, width=0):
+def int2base(x: int, base: int, width: int = 0) -> str:
     """
     Method to convert an int to a base
     Source: http://stackoverflow.com/questions/2267362
@@ -198,7 +199,7 @@ def int2base(x, base, width=0):
     return digits
 
 
-def saferelpath(path, start, strategy="inside"):
+def saferelpath(path: str, start: str, strategy: str = "inside") -> str:
     """
     On Windows relpath will raise a ValueError
     when trying to calculate the relative path to a
@@ -227,13 +228,13 @@ def saferelpath(path, start, strategy="inside"):
 
 class ItemOp:
     @staticmethod
-    def get_by_index(items, index):
+    def get_by_index(items: bpy.types.bpy_prop_collection, index: int) -> Optional[Any]:
         if 0 <= index < len(items):
             return items[index]
         return None
 
     @staticmethod
-    def resize(items: bpy.types.bpy_prop_collection, length: int):
+    def resize(items: bpy.types.bpy_prop_collection, length: int) -> None:
         count = length - len(items)
         if count > 0:
             for i in range(count):
@@ -243,7 +244,7 @@ class ItemOp:
                 items.remove(length)
 
     @staticmethod
-    def add_after(items, index):
+    def add_after(items: bpy.types.bpy_prop_collection, index: int) -> Tuple[Any, int]:
         index_end = len(items)
         index = max(0, min(index_end, index + 1))
         items.add()
@@ -265,7 +266,8 @@ class ItemMoveOp:
     )
 
     @staticmethod
-    def move(items, index, move_type, index_min=0, index_max=None):
+    def move(items: bpy.types.bpy_prop_collection, index: int, move_type: str, 
+             index_min: int = 0, index_max: Optional[int] = None) -> int:
         if index_max is None:
             index_max = len(items) - 1
         else:
@@ -294,7 +296,7 @@ class ItemMoveOp:
         return index_new
 
 
-def deprecated(deprecated_in: Optional[str] = None, details: Optional[str] = None):
+def deprecated(deprecated_in: Optional[str] = None, details: Optional[str] = None) -> Callable:
     """Decorator to mark a function as deprecated.
     Args:
         deprecated_in (Optional[str]): Version in which the function was deprecated.
@@ -303,8 +305,8 @@ def deprecated(deprecated_in: Optional[str] = None, details: Optional[str] = Non
         Callable: The decorated function.
     """
 
-    def _function_wrapper(function: Callable):
-        def _inner_wrapper(*args, **kwargs):
+    def _function_wrapper(function: Callable) -> Callable:
+        def _inner_wrapper(*args: Any, **kwargs: Any) -> Any:
             warn_deprecation(function.__name__, deprecated_in, details)
             return function(*args, **kwargs)
 
@@ -320,7 +322,7 @@ def warn_deprecation(function_name: str, deprecated_in: Optional[str] = None, de
         deprecated_in (Optional[str]): Version in which the function was deprecated.
         details (Optional[str]): Additional details about the deprecation.
     """
-    logging.warning(
+    logger.warning(
         "%s is deprecated%s%s",
         function_name,
         f" since {deprecated_in}" if deprecated_in else "",
@@ -328,7 +330,3 @@ def warn_deprecation(function_name: str, deprecated_in: Optional[str] = None, de
         stack_info=True,
         stacklevel=4,
     )
-
-    # import warnings  # pylint: disable=import-outside-toplevel
-
-    # warnings.warn(f"""{function_name}is deprecated{f" since {deprecated_in}" if deprecated_in else ""}{f": {details}" if details else ""}""", category=DeprecationWarning, stacklevel=2)
diff --git a/cycles_converter.py b/cycles_converter.py
deleted file mode 100644
index f0d391a..0000000
--- a/cycles_converter.py
+++ /dev/null
@@ -1,240 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2012 MMD Tools authors
-# This file is part of MMD Tools.
-
-from typing import Iterable, Optional
-
-import bpy
-
-from .core.shader import _NodeGroupUtils
-from .core.material import FnMaterial
-
-
-def __switchToCyclesRenderEngine():
-    if bpy.context.scene.render.engine != "CYCLES":
-        bpy.context.scene.render.engine = "CYCLES"
-
-
-def __exposeNodeTreeInput(in_socket, name, default_value, node_input, shader):
-    _NodeGroupUtils(shader).new_input_socket(name, in_socket, default_value)
-
-
-def __exposeNodeTreeOutput(out_socket, name, node_output, shader):
-    _NodeGroupUtils(shader).new_output_socket(name, out_socket)
-
-
-def __getMaterialOutput(nodes, bl_idname):
-    o = next((n for n in nodes if n.bl_idname == bl_idname and n.is_active_output), None) or nodes.new(bl_idname)
-    o.is_active_output = True
-    return o
-
-
-def create_MMDAlphaShader():
-    __switchToCyclesRenderEngine()
-
-    if "MMDAlphaShader" in bpy.data.node_groups:
-        return bpy.data.node_groups["MMDAlphaShader"]
-
-    shader = bpy.data.node_groups.new(name="MMDAlphaShader", type="ShaderNodeTree")
-
-    node_input = shader.nodes.new("NodeGroupInput")
-    node_output = shader.nodes.new("NodeGroupOutput")
-    node_output.location.x += 250
-    node_input.location.x -= 500
-
-    trans = shader.nodes.new("ShaderNodeBsdfTransparent")
-    trans.location.x -= 250
-    trans.location.y += 150
-    mix = shader.nodes.new("ShaderNodeMixShader")
-
-    shader.links.new(mix.inputs[1], trans.outputs["BSDF"])
-
-    __exposeNodeTreeInput(mix.inputs[2], "Shader", None, node_input, shader)
-    __exposeNodeTreeInput(mix.inputs["Fac"], "Alpha", 1.0, node_input, shader)
-    __exposeNodeTreeOutput(mix.outputs["Shader"], "Shader", node_output, shader)
-
-    return shader
-
-
-def create_MMDBasicShader():
-    __switchToCyclesRenderEngine()
-
-    if "MMDBasicShader" in bpy.data.node_groups:
-        return bpy.data.node_groups["MMDBasicShader"]
-
-    shader: bpy.types.ShaderNodeTree = bpy.data.node_groups.new(name="MMDBasicShader", type="ShaderNodeTree")
-
-    node_input: bpy.types.NodeGroupInput = shader.nodes.new("NodeGroupInput")
-    node_output: bpy.types.NodeGroupOutput = shader.nodes.new("NodeGroupOutput")
-    node_output.location.x += 250
-    node_input.location.x -= 500
-
-    dif: bpy.types.ShaderNodeBsdfDiffuse = shader.nodes.new("ShaderNodeBsdfDiffuse")
-    dif.location.x -= 250
-    dif.location.y += 150
-    glo: bpy.types.ShaderNodeBsdfAnisotropic = shader.nodes.new("ShaderNodeBsdfAnisotropic")
-    glo.location.x -= 250
-    glo.location.y -= 150
-    mix: bpy.types.ShaderNodeMixShader = shader.nodes.new("ShaderNodeMixShader")
-    shader.links.new(mix.inputs[1], dif.outputs["BSDF"])
-    shader.links.new(mix.inputs[2], glo.outputs["BSDF"])
-
-    __exposeNodeTreeInput(dif.inputs["Color"], "diffuse", [1.0, 1.0, 1.0, 1.0], node_input, shader)
-    __exposeNodeTreeInput(glo.inputs["Color"], "glossy", [1.0, 1.0, 1.0, 1.0], node_input, shader)
-    __exposeNodeTreeInput(glo.inputs["Roughness"], "glossy_rough", 0.0, node_input, shader)
-    __exposeNodeTreeInput(mix.inputs["Fac"], "reflection", 0.02, node_input, shader)
-    __exposeNodeTreeOutput(mix.outputs["Shader"], "shader", node_output, shader)
-
-    return shader
-
-
-def __enum_linked_nodes(node: bpy.types.Node) -> Iterable[bpy.types.Node]:
-    yield node
-    if node.parent:
-        yield node.parent
-    for n in set(l.from_node for i in node.inputs for l in i.links):
-        yield from __enum_linked_nodes(n)
-
-
-def __cleanNodeTree(material: bpy.types.Material):
-    nodes = material.node_tree.nodes
-    node_names = set(n.name for n in nodes)
-    for o in (n for n in nodes if n.bl_idname in {"ShaderNodeOutput", "ShaderNodeOutputMaterial"}):
-        if any(i.is_linked for i in o.inputs):
-            node_names -= set(linked.name for linked in __enum_linked_nodes(o))
-    for name in node_names:
-        nodes.remove(nodes[name])
-
-
-def convertToCyclesShader(obj: bpy.types.Object, use_principled=False, clean_nodes=False, subsurface=0.001):
-    __switchToCyclesRenderEngine()
-    convertToBlenderShader(obj, use_principled, clean_nodes, subsurface)
-
-
-def convertToBlenderShader(obj: bpy.types.Object, use_principled=False, clean_nodes=False, subsurface=0.001):
-    for i in obj.material_slots:
-        if not i.material:
-            continue
-        if not i.material.use_nodes:
-            i.material.use_nodes = True
-            __convertToMMDBasicShader(i.material)
-        if use_principled:
-            __convertToPrincipledBsdf(i.material, subsurface)
-        if clean_nodes:
-            __cleanNodeTree(i.material)
-
-def convertToMMDShader(obj):
-    """BSDF -> MMDShaderDev conversion."""
-    for i in obj.material_slots:
-        if not i.material:
-            continue
-        if not i.material.use_nodes:
-            i.material.use_nodes = True
-        FnMaterial.convert_to_mmd_material(i.material)
-
-def __convertToMMDBasicShader(material: bpy.types.Material):
-    # TODO: test me
-    mmd_basic_shader_grp = create_MMDBasicShader()
-    mmd_alpha_shader_grp = create_MMDAlphaShader()
-
-    if not any(filter(lambda x: isinstance(x, bpy.types.ShaderNodeGroup) and x.node_tree.name in {"MMDBasicShader", "MMDAlphaShader"}, material.node_tree.nodes)):
-        # Add nodes for Cycles Render
-        shader: bpy.types.ShaderNodeGroup = material.node_tree.nodes.new("ShaderNodeGroup")
-        shader.node_tree = mmd_basic_shader_grp
-        shader.inputs[0].default_value[:3] = material.diffuse_color[:3]
-        shader.inputs[1].default_value[:3] = material.specular_color[:3]
-        shader.inputs["glossy_rough"].default_value = 1.0 / getattr(material, "specular_hardness", 50)
-        outplug = shader.outputs[0]
-
-        location = shader.location.copy()
-        location.x -= 1000
-
-        alpha_value = 1.0
-        if len(material.diffuse_color) > 3:
-            alpha_value = material.diffuse_color[3]
-
-        if alpha_value < 1.0:
-            alpha_shader: bpy.types.ShaderNodeGroup = material.node_tree.nodes.new("ShaderNodeGroup")
-            alpha_shader.location.x = shader.location.x + 250
-            alpha_shader.location.y = shader.location.y - 150
-            alpha_shader.node_tree = mmd_alpha_shader_grp
-            alpha_shader.inputs[1].default_value = alpha_value
-            material.node_tree.links.new(alpha_shader.inputs[0], outplug)
-            outplug = alpha_shader.outputs[0]
-
-        material_output: bpy.types.ShaderNodeOutputMaterial = __getMaterialOutput(material.node_tree.nodes, "ShaderNodeOutputMaterial")
-        material.node_tree.links.new(material_output.inputs["Surface"], outplug)
-        material_output.location.x = shader.location.x + 500
-        material_output.location.y = shader.location.y - 150
-
-
-def __convertToPrincipledBsdf(material: bpy.types.Material, subsurface: float):
-    node_names = set()
-    for s in (n for n in material.node_tree.nodes if isinstance(n, bpy.types.ShaderNodeGroup)):
-        if s.node_tree.name == "MMDBasicShader":
-            l: bpy.types.NodeLink
-            for l in s.outputs[0].links:
-                to_node = l.to_node
-                # assuming there is no bpy.types.NodeReroute between MMDBasicShader and MMDAlphaShader
-                if isinstance(to_node, bpy.types.ShaderNodeGroup) and to_node.node_tree.name == "MMDAlphaShader":
-                    __switchToPrincipledBsdf(material.node_tree, s, subsurface, node_alpha=to_node)
-                    node_names.add(to_node.name)
-                else:
-                    __switchToPrincipledBsdf(material.node_tree, s, subsurface)
-            node_names.add(s.name)
-        elif s.node_tree.name == "MMDShaderDev":
-            __switchToPrincipledBsdf(material.node_tree, s, subsurface)
-            node_names.add(s.name)
-    # remove MMD shader nodes
-    nodes = material.node_tree.nodes
-    for name in node_names:
-        nodes.remove(nodes[name])
-
-
-def __switchToPrincipledBsdf(node_tree: bpy.types.NodeTree, node_basic: bpy.types.ShaderNodeGroup, subsurface: float, node_alpha: Optional[bpy.types.ShaderNodeGroup] = None):
-    shader: bpy.types.ShaderNodeBsdfPrincipled = node_tree.nodes.new("ShaderNodeBsdfPrincipled")
-    shader.parent = node_basic.parent
-    shader.location.x = node_basic.location.x
-    shader.location.y = node_basic.location.y
-
-    alpha_socket_name = "Alpha"
-    if node_basic.node_tree.name == "MMDShaderDev":
-        node_alpha, alpha_socket_name = node_basic, "Base Alpha"
-        if "Base Tex" in node_basic.inputs and node_basic.inputs["Base Tex"].is_linked:
-            node_tree.links.new(node_basic.inputs["Base Tex"].links[0].from_socket, shader.inputs["Base Color"])
-        elif "Diffuse Color" in node_basic.inputs:
-            shader.inputs["Base Color"].default_value[:3] = node_basic.inputs["Diffuse Color"].default_value[:3]
-    elif "diffuse" in node_basic.inputs:
-        shader.inputs["Base Color"].default_value[:3] = node_basic.inputs["diffuse"].default_value[:3]
-        if node_basic.inputs["diffuse"].is_linked:
-            node_tree.links.new(node_basic.inputs["diffuse"].links[0].from_socket, shader.inputs["Base Color"])
-
-    shader.inputs["IOR"].default_value = 1.0
-    shader.inputs["Subsurface Weight"].default_value = subsurface
-
-    output_links = node_basic.outputs[0].links
-    if node_alpha:
-        output_links = node_alpha.outputs[0].links
-        shader.parent = node_alpha.parent or shader.parent
-        shader.location.x = node_alpha.location.x
-
-        if alpha_socket_name in node_alpha.inputs:
-            if "Alpha" in shader.inputs:
-                shader.inputs["Alpha"].default_value = node_alpha.inputs[alpha_socket_name].default_value
-                if node_alpha.inputs[alpha_socket_name].is_linked:
-                    node_tree.links.new(node_alpha.inputs[alpha_socket_name].links[0].from_socket, shader.inputs["Alpha"])
-            else:
-                shader.inputs["Transmission"].default_value = 1 - node_alpha.inputs[alpha_socket_name].default_value
-                if node_alpha.inputs[alpha_socket_name].is_linked:
-                    node_invert = node_tree.nodes.new("ShaderNodeMath")
-                    node_invert.parent = shader.parent
-                    node_invert.location.x = node_alpha.location.x - 250
-                    node_invert.location.y = node_alpha.location.y - 300
-                    node_invert.operation = "SUBTRACT"
-                    node_invert.use_clamp = True
-                    node_invert.inputs[0].default_value = 1
-                    node_tree.links.new(node_alpha.inputs[alpha_socket_name].links[0].from_socket, node_invert.inputs[1])
-                    node_tree.links.new(node_invert.outputs[0], shader.inputs["Transmission"])
-
-    for l in output_links:
-        node_tree.links.new(shader.outputs[0], l.to_socket)