Hello Enomoto Takaya,
I enjoyed your game. I liked the simple and clean aesthetic. I also have a few things to note from my play through that might help you with future iterations. I didn't immediately notice the UI in the top left and was initially confused when the game didn't end after a collision. Perhaps it could be bigger and there could be some visual feedback to let you know you have collided. Additionally, there is no feedback when you successfully shoot the box. I think the pellet should be destroyed? But maybe shooting right through it is what you want. The narrow level design feels like a smart choice as that's where my gaze primarily stayed aided by the far travelling pellets which helps keep up the illusion of moving long distances at high speed. However, the box often drew my gaze away from this clever level design when it went outside the bounds of level. This is when it became apparent that the box's movement is tied to the button the player is pressing, which cheapened the feeling of hitting it thereafter. I also found a bug. If you hold right or left long enough you will fall out of the map and cannot restart the game. I hope this feedback helps you. This is an interesting take on 3D Death Chase. Keep up the great work! :)
-Z