diff --git a/Assets/VRM10/Runtime/Components/VRM10Object/VRM10ObjectExpression.cs b/Assets/VRM10/Runtime/Components/VRM10Object/VRM10ObjectExpression.cs
index e9a99e213..ca4b8bc99 100644
--- a/Assets/VRM10/Runtime/Components/VRM10Object/VRM10ObjectExpression.cs
+++ b/Assets/VRM10/Runtime/Components/VRM10Object/VRM10ObjectExpression.cs
@@ -9,6 +9,8 @@ namespace UniVRM10
     [Serializable]
     public sealed class VRM10ObjectExpression
     {
+        public const string NEUTRAL_KEY = "Neutral";
+
         #region Preset
         [SerializeField, Header("Emotion")]
         public VRM10Expression Happy;
diff --git a/Assets/VRM10/Runtime/IO/Vrm10Importer.cs b/Assets/VRM10/Runtime/IO/Vrm10Importer.cs
index 0468fd08a..82dcc4a3b 100644
--- a/Assets/VRM10/Runtime/IO/Vrm10Importer.cs
+++ b/Assets/VRM10/Runtime/IO/Vrm10Importer.cs
@@ -427,6 +427,14 @@ namespace UniVRM10
                     {
                         var key = ExpressionKey.CreateCustom(name);
                         var preset = ExpressionPreset.custom;
+                        if (preset == ExpressionPreset.custom && name == VRM10ObjectExpression.NEUTRAL_KEY)
+                        {
+                            // TODO:
+                            // 注意！JsonSchema の更新待ち？
+                            key = ExpressionKey.CreateFromPreset(ExpressionPreset.neutral);
+                            Debug.Log($"set neutral");
+                            preset = ExpressionPreset.neutral;
+                        }
                         var clip = GetOrLoadExpression(key.SubAssetKey, preset, expression);
                         if (clip != null)
                         {
diff --git a/Assets/VRM10/Runtime/Migration/MigrationVrm.cs b/Assets/VRM10/Runtime/Migration/MigrationVrm.cs
index e0039714f..294ac93dd 100644
--- a/Assets/VRM10/Runtime/Migration/MigrationVrm.cs
+++ b/Assets/VRM10/Runtime/Migration/MigrationVrm.cs
@@ -40,6 +40,20 @@ namespace UniVRM10
             return MigrateVrm(gltf, bin, data.Json.ParseAsJson()["extensions"]["VRM"]);
         }
 
+        /// <summary>
+        /// dst が null の場合だけ代入する。
+        /// 先に来た方を有効にしたい。
+        /// </summary>
+        /// <param name="dst"></param>
+        /// <param name="src"></param>
+        static void SetIfNull(ref UniGLTF.Extensions.VRMC_vrm.Expression dst, UniGLTF.Extensions.VRMC_vrm.Expression src)
+        {
+            if (dst == null)
+            {
+                dst = src;
+            }
+        }
+
         static byte[] MigrateVrm(glTF gltf, ArraySegment<byte> bin, JsonNode vrm0)
         {
             var meshToNode = CreateMeshToNode(gltf);
@@ -65,25 +79,38 @@ namespace UniVRM10
                     {
                         switch (preset)
                         {
-                            case ExpressionPreset.happy: vrm1.Expressions.Preset.Happy = expression; break;
-                            case ExpressionPreset.angry: vrm1.Expressions.Preset.Angry = expression; break;
-                            case ExpressionPreset.sad: vrm1.Expressions.Preset.Sad = expression; break;
-                            case ExpressionPreset.relaxed: vrm1.Expressions.Preset.Relaxed = expression; break;
-                            case ExpressionPreset.surprised: vrm1.Expressions.Preset.Surprised = expression; break;
-                            case ExpressionPreset.aa: vrm1.Expressions.Preset.Aa = expression; break;
-                            case ExpressionPreset.ih: vrm1.Expressions.Preset.Ih = expression; break;
-                            case ExpressionPreset.ou: vrm1.Expressions.Preset.Ou = expression; break;
-                            case ExpressionPreset.ee: vrm1.Expressions.Preset.Ee = expression; break;
-                            case ExpressionPreset.oh: vrm1.Expressions.Preset.Oh = expression; break;
-                            case ExpressionPreset.blink: vrm1.Expressions.Preset.Blink = expression; break;
-                            case ExpressionPreset.blinkLeft: vrm1.Expressions.Preset.BlinkLeft = expression; break;
-                            case ExpressionPreset.blinkRight: vrm1.Expressions.Preset.BlinkRight = expression; break;
-                            case ExpressionPreset.lookUp: vrm1.Expressions.Preset.LookUp = expression; break;
-                            case ExpressionPreset.lookDown: vrm1.Expressions.Preset.LookDown = expression; break;
-                            case ExpressionPreset.lookLeft: vrm1.Expressions.Preset.LookLeft = expression; break;
-                            case ExpressionPreset.lookRight: vrm1.Expressions.Preset.LookRight = expression; break;
-                            case ExpressionPreset.neutral: vrm1.Expressions.Custom[customName] = expression; break;
-                            case ExpressionPreset.custom: vrm1.Expressions.Custom[customName] = expression; break;
+                            case ExpressionPreset.happy: SetIfNull(ref vrm1.Expressions.Preset.Happy, expression); break;
+                            case ExpressionPreset.angry: SetIfNull(ref vrm1.Expressions.Preset.Angry, expression); break;
+                            case ExpressionPreset.sad: SetIfNull(ref vrm1.Expressions.Preset.Sad, expression); break;
+                            case ExpressionPreset.relaxed: SetIfNull(ref vrm1.Expressions.Preset.Relaxed, expression); break;
+                            case ExpressionPreset.surprised: SetIfNull(ref vrm1.Expressions.Preset.Surprised, expression); break;
+                            case ExpressionPreset.aa: SetIfNull(ref vrm1.Expressions.Preset.Aa, expression); break;
+                            case ExpressionPreset.ih: SetIfNull(ref vrm1.Expressions.Preset.Ih, expression); break;
+                            case ExpressionPreset.ou: SetIfNull(ref vrm1.Expressions.Preset.Ou, expression); break;
+                            case ExpressionPreset.ee: SetIfNull(ref vrm1.Expressions.Preset.Ee, expression); break;
+                            case ExpressionPreset.oh: SetIfNull(ref vrm1.Expressions.Preset.Oh, expression); break;
+                            case ExpressionPreset.blink: SetIfNull(ref vrm1.Expressions.Preset.Blink, expression); break;
+                            case ExpressionPreset.blinkLeft: SetIfNull(ref vrm1.Expressions.Preset.BlinkLeft, expression); break;
+                            case ExpressionPreset.blinkRight: SetIfNull(ref vrm1.Expressions.Preset.BlinkRight, expression); break;
+                            case ExpressionPreset.lookUp: SetIfNull(ref vrm1.Expressions.Preset.LookUp, expression); break;
+                            case ExpressionPreset.lookDown: SetIfNull(ref vrm1.Expressions.Preset.LookDown, expression); break;
+                            case ExpressionPreset.lookLeft: SetIfNull(ref vrm1.Expressions.Preset.LookLeft, expression); break;
+                            case ExpressionPreset.lookRight: SetIfNull(ref vrm1.Expressions.Preset.LookRight, expression); break;
+                            case ExpressionPreset.neutral:
+                                // TODO: 仕様確定待ち
+                                // Presetに格上げするか、小文字にする
+                                vrm1.Expressions.Custom[VRM10ObjectExpression.NEUTRAL_KEY] = expression;
+                                break;
+                            case ExpressionPreset.custom:
+                                if (vrm1.Expressions.Custom.ContainsKey(customName))
+                                {
+                                    // 同名が既存。不採用
+                                }
+                                else
+                                {
+                                    vrm1.Expressions.Custom[customName] = expression;
+                                }
+                                break;
                             default: throw new NotImplementedException();
                         }
                     }
diff --git a/Assets/VRM10/Runtime/Migration/MigrationVrmExpression.cs b/Assets/VRM10/Runtime/Migration/MigrationVrmExpression.cs
index b0eb44603..628863a98 100644
--- a/Assets/VRM10/Runtime/Migration/MigrationVrmExpression.cs
+++ b/Assets/VRM10/Runtime/Migration/MigrationVrmExpression.cs
@@ -8,12 +8,29 @@ namespace UniVRM10
 {
     public static class MigrationVrmExpression
     {
-        static ExpressionPreset ToPreset(JsonNode json)
+        /// <summary>
+        /// preset 名の文字列から ExpressionPreset を確定させる。
+        /// 
+        /// 0.x の特殊な挙動として、
+        /// preset名が "unknown" の場合に、
+        /// "name" を preset 名として解釈を試みる。
+        /// </summary>
+        /// <param name="json"></param>
+        /// <param name="name"></param>
+        /// <returns></returns>
+        static ExpressionPreset ToPreset(JsonNode json, string name)
         {
-            switch (json.GetString().ToLower())
+            var src = json.GetString().ToLowerInvariant();
+            if (src == "unknown")
             {
-                case "unknown": return ExpressionPreset.custom;
+                // VRM 0.x では以下の実装が存在した。
+                // Preset が unknown で Name が Joy の表情があったときに
+                // それは Preset が Joy であるとみなしてロードしていた。
+                src = name.ToLowerInvariant();
+            }
 
+            switch (src)
+            {
                 // https://github.com/vrm-c/vrm-specification/issues/185
                 case "neutral": return ExpressionPreset.neutral;
 
@@ -39,7 +56,7 @@ namespace UniVRM10
                 case "lookright": return ExpressionPreset.lookRight;
             }
 
-            throw new NotImplementedException();
+            return ExpressionPreset.custom;
         }
 
         static IEnumerable<UniGLTF.Extensions.VRMC_vrm.MorphTargetBind> ToMorphTargetBinds(JsonNode json,
@@ -199,7 +216,7 @@ namespace UniVRM10
                 {
                     isBinary = isBinaryNode.GetBoolean();
                 }
-                var preset = ToPreset(blendShapeClip["presetName"]);
+                var preset = ToPreset(blendShapeClip["presetName"], name);
                 var expression = new UniGLTF.Extensions.VRMC_vrm.Expression
                 {
                     IsBinary = isBinary,