diff --git a/Assets/VRM10/Runtime/IO/Vrm10.cs b/Assets/VRM10/Runtime/IO/Vrm10.cs
index daf3b51c6..c28e25e0b 100644
--- a/Assets/VRM10/Runtime/IO/Vrm10.cs
+++ b/Assets/VRM10/Runtime/IO/Vrm10.cs
@@ -44,6 +44,11 @@ namespace UniVRM10
             VrmMetaInformationCallback vrmMetaInformationCallback = null,
             CancellationToken ct = default)
         {
+            if (awaitCaller == null)
+            {
+                awaitCaller = new ImmediateCaller();
+            }
+
             return await LoadAsync(
                 path,
                 System.IO.File.ReadAllBytes(path),
@@ -81,6 +86,11 @@ namespace UniVRM10
             VrmMetaInformationCallback vrmMetaInformationCallback = null,
             CancellationToken ct = default)
         {
+            if (awaitCaller == null)
+            {
+                awaitCaller = new ImmediateCaller();
+            }
+
             return await LoadAsync(
                 string.Empty,
                 bytes,
@@ -105,7 +115,6 @@ namespace UniVRM10
             CancellationToken ct)
         {
             ct.ThrowIfCancellationRequested();
-
             if (awaitCaller == null)
             {
                 throw new ArgumentNullException();
@@ -172,6 +181,10 @@ namespace UniVRM10
             CancellationToken ct)
         {
             ct.ThrowIfCancellationRequested();
+            if (awaitCaller == null)
+            {
+                throw new ArgumentNullException();
+            }
 
             var vrm10Data = await awaitCaller.Run(() => Vrm10Data.Parse(gltfData));
             ct.ThrowIfCancellationRequested();
@@ -203,6 +216,10 @@ namespace UniVRM10
             CancellationToken ct)
         {
             ct.ThrowIfCancellationRequested();
+            if (awaitCaller == null)
+            {
+                throw new ArgumentNullException();
+            }
 
             Vrm10Data migratedVrm10Data = default;
             MigrationData migrationData = default;
@@ -243,6 +260,10 @@ namespace UniVRM10
             CancellationToken ct)
         {
             ct.ThrowIfCancellationRequested();
+            if (awaitCaller == null)
+            {
+                throw new ArgumentNullException();
+            }
 
             if (vrm10Data == null)
             {
diff --git a/Assets/VRM10_Samples/VRM10FirstPersonSample/VRM10RuntimeLoader.cs b/Assets/VRM10_Samples/VRM10FirstPersonSample/VRM10RuntimeLoader.cs
index bcd5fd278..3a0feb381 100644
--- a/Assets/VRM10_Samples/VRM10FirstPersonSample/VRM10RuntimeLoader.cs
+++ b/Assets/VRM10_Samples/VRM10FirstPersonSample/VRM10RuntimeLoader.cs
@@ -86,7 +86,7 @@ namespace UniVRM10.FirstPersonSample
 
         async Task<Vrm10Instance> LoadAsync(string path, VRMShaders.IAwaitCaller awaitCaller)
         {
-            var instance = await Vrm10.LoadPathAsync(path);
+            var instance = await Vrm10.LoadPathAsync(path, awaitCaller: awaitCaller);
 
             // VR用 FirstPerson 設定
             await instance.Vrm.FirstPerson.SetupAsync(instance.gameObject, awaitCaller);