Load saves then check the bathroom at night when you see momoko that mean kimiko hasn't arrived yet so tell momoko to not lock the door while taking a bath also corrupt momoko more
The problem with that is that you and me don't have the same saves tho :/ by I have no idea what save it is , I mean that amongs my set of saves I don't know which one would be the closest ... if even any would be remotely close , because when as far as i remember the bathroom I had it for a long time and I was sure that it was able to do later in the game , and now that task is literally the only thing i have left.