diff --git a/packages/three-vrm-materials-mtoon/examples/feature-test.html b/packages/three-vrm-materials-mtoon/examples/feature-test.html
index dd3b29f3e..ba7d447a6 100644
--- a/packages/three-vrm-materials-mtoon/examples/feature-test.html
+++ b/packages/three-vrm-materials-mtoon/examples/feature-test.html
@@ -270,11 +270,57 @@
 
 				},
 
+				// outline world
+				{
+					map: textureUVGrid,
+					outlineWidthMode: 'worldCoordinates',
+					outlineWidthFactor: 0.05,
+					outlineColorFactor: 0x00ff00,
+				},
+
+				// outline world, masked, unlit
+				{
+					map: textureUVGrid,
+					outlineWidthMode: 'worldCoordinates',
+					outlineWidthFactor: 0.05,
+					outlineColorFactor: 0x00ff00,
+					outlineWidthMultiplyTexture: textureBinaryHalf,
+					outlineLightingMixFactor: 0.0,
+				},
+
+				// outline screen
+				{
+					map: textureUVGrid,
+					outlineWidthMode: 'screenCoordinates',
+					outlineWidthFactor: 0.05,
+					outlineColorFactor: 0xff0000,
+				},
+
 			].map( ( params, i ) => {
 
 				const material = new MToonMaterial( params );
 				const mesh = new THREE.Mesh( geometrySphere, material );
 
+				// if outline is enabled we need to duplicate the material and assign it to the mesh
+				if ( material.outlineWidthMode !== 'none' ) {
+
+					// duplicate the material for outline use
+					const materialOutline = mesh.material.clone();
+					materialOutline.isOutline = true;
+					materialOutline.side = THREE.BackSide;
+
+					mesh.material = [ mesh.material, materialOutline ];
+
+					// make two geometry groups out of a same buffer
+					const geometry = mesh.geometry; // mesh.geometry is guaranteed to be a BufferGeometry in GLTFLoader
+					const primitiveVertices = geometry.index ? geometry.index.count : geometry.attributes.position.count / 3;
+					geometry.addGroup( 0, primitiveVertices, 0 );
+					geometry.addGroup( 0, primitiveVertices, 1 );
+
+				}
+
+				console.log( mesh.material );
+
 				const x = ( i % 5 ) - 2.0;
 				const y = Math.floor( i / 5 ) - 2.0;
 				mesh.position.set( x, y, 0 );
@@ -309,7 +355,20 @@
 
 				for ( const mesh of meshes ) {
 
-					mesh.material.update( delta );
+					// mesh.material can be either array or single material
+					if ( Array.isArray( mesh.material ) ) {
+
+						for ( const material of mesh.material ) {
+
+							material.update( delta );
+
+						}
+
+					} else {
+
+						mesh.material.update( delta );
+
+					}
 
 				}
 
diff --git a/packages/three-vrm-materials-mtoon/examples/webgpu-feature-test.html b/packages/three-vrm-materials-mtoon/examples/webgpu-feature-test.html
index f8c540055..e884a8b91 100644
--- a/packages/three-vrm-materials-mtoon/examples/webgpu-feature-test.html
+++ b/packages/three-vrm-materials-mtoon/examples/webgpu-feature-test.html
@@ -273,11 +273,55 @@
 
 				},
 
+				// outline world
+				{
+					map: textureUVGrid,
+					outlineWidthMode: 'worldCoordinates',
+					outlineWidthFactor: 0.05,
+					outlineColorFactor: 0x00ff00,
+				},
+
+				// outline world, masked, unlit
+				{
+					map: textureUVGrid,
+					outlineWidthMode: 'worldCoordinates',
+					outlineWidthFactor: 0.05,
+					outlineColorFactor: 0x00ff00,
+					outlineWidthMultiplyTexture: textureBinaryHalf,
+					outlineLightingMixFactor: 0.0,
+				},
+
+				// outline screen
+				{
+					map: textureUVGrid,
+					outlineWidthMode: 'screenCoordinates',
+					outlineWidthFactor: 0.05,
+					outlineColorFactor: 0xff0000,
+				},
+
 			].map( ( params, i ) => {
 
 				const material = new MToonNodeMaterial( params );
 				const mesh = new THREE.Mesh( geometrySphere, material );
 
+				// if outline is enabled we need to duplicate the material and assign it to the mesh
+				if ( params.outlineWidthMode !== 'none' ) {
+
+					// duplicate the material for outline use
+					const materialOutline = mesh.material.clone();
+					materialOutline.isOutline = true;
+					materialOutline.side = THREE.BackSide;
+
+					mesh.material = [ mesh.material, materialOutline ];
+
+					// make two geometry groups out of a same buffer
+					const geometry = mesh.geometry; // mesh.geometry is guaranteed to be a BufferGeometry in GLTFLoader
+					const primitiveVertices = geometry.index ? geometry.index.count : geometry.attributes.position.count / 3;
+					geometry.addGroup( 0, primitiveVertices, 0 );
+					geometry.addGroup( 0, primitiveVertices, 1 );
+
+				}
+
 				const x = ( i % 5 ) - 2.0;
 				const y = Math.floor( i / 5 ) - 2.0;
 				mesh.position.set( x, y, 0 );
@@ -312,7 +356,20 @@
 
 				for ( const mesh of meshes ) {
 
-					mesh.material.update( delta );
+					// mesh.material can be either array or single material
+					if ( Array.isArray( mesh.material ) ) {
+
+						for ( const material of mesh.material ) {
+
+							material.update( delta );
+
+						}
+
+					} else {
+
+						mesh.material.update( delta );
+
+					}
 
 				}
 
diff --git a/packages/three-vrm-materials-mtoon/src/MToonMaterial.ts b/packages/three-vrm-materials-mtoon/src/MToonMaterial.ts
index 5ec1fb16f..76774ac88 100644
--- a/packages/three-vrm-materials-mtoon/src/MToonMaterial.ts
+++ b/packages/three-vrm-materials-mtoon/src/MToonMaterial.ts
@@ -606,7 +606,6 @@ export class MToonMaterial extends THREE.ShaderMaterial {
       DEBUG_NORMAL: this._debugMode === 'normal',
       DEBUG_LITSHADERATE: this._debugMode === 'litShadeRate',
       DEBUG_UV: this._debugMode === 'uv',
-      OUTLINE_WIDTH_WORLD: this._isOutline && this._outlineWidthMode === MToonMaterialOutlineWidthMode.WorldCoordinates,
       OUTLINE_WIDTH_SCREEN:
         this._isOutline && this._outlineWidthMode === MToonMaterialOutlineWidthMode.ScreenCoordinates,
     };
diff --git a/packages/three-vrm-materials-mtoon/src/shaders/mtoon.vert b/packages/three-vrm-materials-mtoon/src/shaders/mtoon.vert
index 72664cfa2..f1815e97b 100644
--- a/packages/three-vrm-materials-mtoon/src/shaders/mtoon.vert
+++ b/packages/three-vrm-materials-mtoon/src/shaders/mtoon.vert
@@ -92,27 +92,22 @@ void main() {
 
   vViewPosition = - mvPosition.xyz;
 
-  float outlineTex = 1.0;
-
   #ifdef OUTLINE
+    float worldNormalLength = length( transformedNormal );
+    vec3 outlineOffset = outlineWidthFactor * worldNormalLength * objectNormal;
+
     #ifdef USE_OUTLINEWIDTHMULTIPLYTEXTURE
       vec2 outlineWidthMultiplyTextureUv = ( outlineWidthMultiplyTextureUvTransform * vec3( vUv, 1 ) ).xy;
-      outlineTex = texture2D( outlineWidthMultiplyTexture, outlineWidthMultiplyTextureUv ).g;
-    #endif
-
-    #ifdef OUTLINE_WIDTH_WORLD
-      float worldNormalLength = length( transformedNormal );
-      vec3 outlineOffset = outlineWidthFactor * outlineTex * worldNormalLength * objectNormal;
-      gl_Position = projectionMatrix * modelViewMatrix * vec4( outlineOffset + transformed, 1.0 );
+      float outlineTex = texture2D( outlineWidthMultiplyTexture, outlineWidthMultiplyTextureUv ).g;
+      outlineOffset *= outlineTex;
     #endif
 
     #ifdef OUTLINE_WIDTH_SCREEN
-      vec3 clipNormal = ( projectionMatrix * modelViewMatrix * vec4( objectNormal, 0.0 ) ).xyz;
-      vec2 projectedNormal = normalize( clipNormal.xy );
-      projectedNormal.x *= projectionMatrix[ 0 ].x / projectionMatrix[ 1 ].y;
-      gl_Position.xy += 2.0 * outlineWidthFactor * outlineTex * projectedNormal.xy;
+      outlineOffset *= vViewPosition.z / projectionMatrix[ 1 ].y;
     #endif
 
+    gl_Position = projectionMatrix * modelViewMatrix * vec4( outlineOffset + transformed, 1.0 );
+
     gl_Position.z += 1E-6 * gl_Position.w; // anti-artifact magic
   #endif