diff --git a/packages/frontend/assets/room/rooms/default/300-ceiling.glb b/packages/frontend/assets/room/rooms/default/300-ceiling.glb
index 1d3c0ef6de..8dead4de58 100644
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diff --git a/packages/frontend/assets/room/rooms/default/300-floor.glb b/packages/frontend/assets/room/rooms/default/300-floor.glb
index a56ec29009..0dafed8f20 100644
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diff --git a/packages/frontend/assets/room/rooms/default/300-wall-demado.glb b/packages/frontend/assets/room/rooms/default/300-wall-demado.glb
index b578857484..85f6eae9ef 100644
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diff --git a/packages/frontend/assets/room/rooms/default/300-wall.glb b/packages/frontend/assets/room/rooms/default/300-wall.glb
index 88f18dd787..cbde2efd87 100644
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diff --git a/packages/frontend/assets/room/rooms/default/300.glb b/packages/frontend/assets/room/rooms/default/300.glb
new file mode 100644
index 0000000000..157e53139b
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diff --git a/packages/frontend/assets/room/rooms/default/default.blend b/packages/frontend/assets/room/rooms/default/default.blend
index 80975c313d..633461daa0 100644
Binary files a/packages/frontend/assets/room/rooms/default/default.blend and b/packages/frontend/assets/room/rooms/default/default.blend differ
diff --git a/packages/frontend/assets/world/lobby/dummy-ads/angry_ai.png b/packages/frontend/assets/world/lobby/dummy-ads/angry_ai.png
new file mode 100644
index 0000000000..4450c6dc0f
Binary files /dev/null and b/packages/frontend/assets/world/lobby/dummy-ads/angry_ai.png differ
diff --git a/packages/frontend/src/world/engine.ts b/packages/frontend/src/world/engine.ts
index ee4e0e50b4..d62d335e1a 100644
--- a/packages/frontend/src/world/engine.ts
+++ b/packages/frontend/src/world/engine.ts
@@ -474,7 +474,7 @@ export class WorldEngine extends EventEmitter<WorldEngineEvents> {
 				adMesh.parent = adRoot;
 				adMesh.position = new BABYLON.Vector3(cm(0), cm(0), cm(7500));
 
-				const tex = new BABYLON.Texture(`/client-assets/world/lobby/dummy-ads/${1 + Math.floor(Math.random() * 4)}.png`, this.scene);
+				const tex = new BABYLON.Texture('/client-assets/world/lobby/dummy-ads/angry_ai.png', this.scene);
 				const adMat = new BABYLON.StandardMaterial(`ad_${j}_${i}_mat`, this.scene);
 				adMat.emissiveTexture = tex;
 				adMat.disableLighting = true;
diff --git a/packages/frontend/src/world/room/engine.ts b/packages/frontend/src/world/room/engine.ts
index a17ddcfcdf..18cd36970b 100644
--- a/packages/frontend/src/world/room/engine.ts
+++ b/packages/frontend/src/world/room/engine.ts
@@ -183,7 +183,6 @@ export class RoomEngine extends EventEmitter<RoomEngineEvents> {
 	}
 
 	private time: 0 | 1 | 2 = 0; // 0: 昼, 1: 夕, 2: 夜
-	private roomCollisionMeshes: BABYLON.AbstractMesh[] = [];
 	public roomState: RoomState;
 
 	private _gridSnapping = { enabled: true, scale: cm(4) };
@@ -280,6 +279,12 @@ export class RoomEngine extends EventEmitter<RoomEngineEvents> {
 		this.envMapOutdoor = BABYLON.CubeTexture.CreateFromPrefilteredData(this.time === 2 ? '/client-assets/room/outdoor-night.env' : '/client-assets/room/outdoor-day.env', this.scene);
 		this.envMapOutdoor.level = this.time === 0 ? 0.5 : this.time === 1 ? 0.3 : 0.1;
 
+		const roomCollisionCube = BABYLON.MeshBuilder.CreateBox('roomCollisionCube', { size: cm(300) }, this.scene);
+		roomCollisionCube.position.y = cm(150);
+		roomCollisionCube.scaling.x = -1; // flip normals
+		roomCollisionCube.isVisible = false;
+		roomCollisionCube.checkCollisions = true;
+
 		this.scene.collisionsEnabled = true;
 
 		this.camera = new BABYLON.UniversalCamera('camera', new BABYLON.Vector3(0, cm(130), cm(0)), this.scene);
@@ -800,12 +805,11 @@ export class RoomEngine extends EventEmitter<RoomEngineEvents> {
 
 		for (const mesh of meshes) {
 			for (const m of mesh.getChildMeshes()) {
-				if (m.name.includes('__ROOM_WALL__') || m.name.includes('__ROOM_SIDE__') || m.name.includes('__ROOM_FLOOR__') || m.name.includes('__ROOM_CEILING__') || m.name.includes('__ROOM_TOP__')) {
+				if (m.name.includes('__ROOM_WALL__') || m.name.includes('__ROOM_SIDE__') || m.name.includes('__ROOM_FLOOR__') || m.name.includes('__ROOM_CEILING__') || m.name.includes('__ROOM_TOP__') || m.name.includes('__ROOM_BOTTOM__')) {
 					m.isPickable = false;
 					m.receiveShadows = false;
 					m.isVisible = false;
-					m.checkCollisions = true;
-					this.roomCollisionMeshes.push(m);
+					m.checkCollisions = false;
 					continue;
 				}