Maki lives with her son Takashi. Takashi rarely responds when Maki talks to him, so Maki lives a lonely life. Then one morning, Maki and her son wake up to find themselves sleeping in a room they don't recognize. The door is locked and it doesn't look like it can be opened at all. The two are trapped and at a loss, but Takashi notices a note on the wall. It says something that shocks them...