Very interesting game. One suggestion/request: it would be great if Oni's uniform (particularly the one she puts on in her room in the beginning) became more worn/damaged the further the plot progresses. This could be in response to plot events, rather than damage taken, since there seems to be little physical damage in the game so far. The separate damaged version of the uniform is what gives the idea.
Since it's made of a tight, stretchy fabric, we could gradually see it become first dirty, then ripped, eventually to the point where the sleeves are torn off, she loses and/or breaks her heels, etc. By the end of the game, if the player has stuck with her default uniform the whole time, it becomes completely wrecked. (Maybe this could be tied to an achievement in the final release?) May or may not apply to other clothes, depending on material's susceptibility to damage.