Miyuki Sone

After purchasing the game You and Me and Her because you enjoyed DDLC, a very similar game, you play through it for a bit and finish Miyuki's route, so you move on to Aoi's route. As you play through Aoi's route, you notice Miyuki breaking the fourth wall a lot, but think nothing of it, assuming it's just a game feature. That's at least until she proves to you that it wasn't simply a 'game feature' in the most unexpected way possible...