diff --git a/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs b/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs
index f261057c9..f354671d0 100644
--- a/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs
+++ b/Assets/UniGLTF/Editor/UniGLTF/ScriptedImporter/ScriptedImporterImpl.cs
@@ -1,4 +1,4 @@
-
+using System.Collections.Generic;
 using System.Linq;
 using UnityEditor.Experimental.AssetImporters;
 using UnityEngine;
@@ -7,70 +7,100 @@ namespace UniGLTF
 {
     public static class ScriptedImporterImpl
     {
-        public static void Import(ScriptedImporter scriptedImporter, AssetImportContext importerContext, Axises reverseAxis)
+        /// <summary>
+        /// glb をパースして、UnityObject化、さらにAsset化する
+        /// </summary>
+        /// <param name="scriptedImporter"></param>
+        /// <param name="context"></param>
+        /// <param name="reverseAxis"></param>
+        public static void Import(ScriptedImporter scriptedImporter, AssetImportContext context, Axises reverseAxis)
         {
 #if VRM_DEVELOP            
-            Debug.Log("OnImportAsset to " + importerContext.assetPath);
+            Debug.Log("OnImportAsset to " + context.assetPath);
 #endif
 
+            var loaded = Load(context.assetPath,
+                scriptedImporter.GetExternalObjectMap().Select(kv => (kv.Key.name, kv.Value)),
+                reverseAxis
+            );
+
+            AddSubAssets(context, loaded);
+        }
+
+        /// <summary>
+        /// Parse して、UnityObject 化する。
+        /// 
+        /// TODO: すべての UnityObject を ImporterContext が所有する。(Disposeで削除できる)
+        /// </summary>
+        /// <param name="assetPath">glbのパス</param>
+        /// <param name="externalObjectMap">ScriptedImporter外部に作成済みのAssetへの参照</param>
+        /// <param name="reverseAxis">gltf から unityへの座標変換オプション</param>
+        /// <returns></returns>
+        static ImporterContext Load(string assetPath, IEnumerable<(string, UnityEngine.Object)> externalObjectMap, Axises reverseAxis)
+        {
             //
             // Parse(parse glb, parser gltf json)
             //
             var parser = new GltfParser();
-            parser.ParsePath(importerContext.assetPath);
+            parser.ParsePath(assetPath);
 
             //
             // Import(create unity objects)
             //
-            var context = new ImporterContext(parser, null,
-                scriptedImporter.GetExternalObjectMap()
-                    .Select(kv => (kv.Key.name, kv.Value))
-            );
+            var context = new ImporterContext(parser, null, externalObjectMap);
             context.InvertAxis = reverseAxis;
             context.Load();
             context.ShowMeshes();
 
-            //
-            // SubAsset
-            //
+            return context;
+        }
 
+        /// <summary>
+        /// UnityObjectをSubAsset化する。
+        /// 
+        /// TODO: SubAsset化されると、ImporterContext から所有権を除去する
+        /// </summary>
+        /// <param name="context"></param>
+        /// <param name="loaded"></param>
+        static void AddSubAssets(AssetImportContext context, ImporterContext loaded)
+        {
             // Texture
-            foreach (var info in context.TextureFactory.Textures)
+            foreach (var info in loaded.TextureFactory.Textures)
             {
                 if (info.IsSubAsset)
                 {
                     var texture = info.Texture;
-                    importerContext.AddObjectToAsset(texture.name, texture);
+                    context.AddObjectToAsset(texture.name, texture);
                 }
             }
 
             // Material
-            foreach (var info in context.MaterialFactory.Materials)
+            foreach (var info in loaded.MaterialFactory.Materials)
             {
                 if (info.IsSubAsset)
                 {
                     var material = info.Asset;
-                    importerContext.AddObjectToAsset(material.name, material);
+                    context.AddObjectToAsset(material.name, material);
                 }
             }
 
             // Mesh
-            foreach (var mesh in context.Meshes.Select(x => x.Mesh))
+            foreach (var mesh in loaded.Meshes.Select(x => x.Mesh))
             {
                 // all mesh is subasset
-                importerContext.AddObjectToAsset(mesh.name, mesh);
+                context.AddObjectToAsset(mesh.name, mesh);
             }
 
             // Animation
-            foreach (var clip in context.AnimationClips)
+            foreach (var clip in loaded.AnimationClips)
             {
                 // all animation is subasset
-                importerContext.AddObjectToAsset(clip.name, clip);
+                context.AddObjectToAsset(clip.name, clip);
             }
 
             // Root GameObject is main object
-            importerContext.AddObjectToAsset(context.Root.name, context.Root);
-            importerContext.SetMainObject(context.Root);
+            context.AddObjectToAsset(loaded.Root.name, loaded.Root);
+            context.SetMainObject(loaded.Root);
         }
     }
 }