Changing screen size is a mistake, I can't think on anyone changing the screen size ingame with the mouse wheel so chaotically, it's not unplayeable, but it ain't a challenge either, loved the sprites and ringo and her theme as well, fonts are quite hard to read and it should be pointed more directly that mimi chan becomes the mouse.
Other than that, it's quite good, the shopping system works wonders (I didn't need the hitbox though), danmaku is enjoyable and loved the ending.