diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs
index d9ed0dba9..03dd3db36 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/ImporterContext.cs
@@ -19,6 +19,14 @@ namespace UniGLTF
         public AnimationClipFactory AnimationClipFactory { get; }
         public IReadOnlyDictionary<SubAssetKey, UnityEngine.Object> ExternalObjectMap;
 
+        /// <summary>
+        /// UnityObject の 生成(LoadAsync) と 破棄(Dispose) を行う。
+        /// LoadAsync が成功した場合、返り値(RuntimeGltfInstance) に破棄する責務を移動させる。
+        /// </summary>
+        /// <param name="data">Jsonからデシリアライズされた GLTF 情報など</param>
+        /// <param name="externalObjectMap">外部オブジェクトのリスト(主にScriptedImporterのRemapで使う)</param>
+        /// <param name="textureDeserializer">Textureロードをカスタマイズする</param>
+        /// <param name="materialGenerator">Materialロードをカスタマイズする(URP向け)</param>
         public ImporterContext(
             GltfData data,
             IReadOnlyDictionary<SubAssetKey, UnityEngine.Object> externalObjectMap = null,
diff --git a/Assets/VRM/Runtime/IO/VRMImporterContext.cs b/Assets/VRM/Runtime/IO/VRMImporterContext.cs
index 199c32fcf..c085f6bd6 100644
--- a/Assets/VRM/Runtime/IO/VRMImporterContext.cs
+++ b/Assets/VRM/Runtime/IO/VRMImporterContext.cs
@@ -26,11 +26,10 @@ namespace VRM
             IReadOnlyDictionary<SubAssetKey, Object> externalObjectMap = null,
             ITextureDeserializer textureDeserializer = null,
             IMaterialDescriptorGenerator materialGenerator = null)
-            : base(data.Data, externalObjectMap, textureDeserializer)
+            : base(data.Data, externalObjectMap, textureDeserializer, materialGenerator ?? new VRMMaterialDescriptorGenerator(data.VrmExtensions))
         {
             _data = data;
             TextureDescriptorGenerator = new VrmTextureDescriptorGenerator(Data, VRM);
-            MaterialDescriptorGenerator = materialGenerator ?? new VRMMaterialDescriptorGenerator(VRM);
         }
 
         #region OnLoad