Chinatsu receives a house key from her kind and successful boyfriend Keigo (Yoshihiko Arima) as a birthday gift. With this gift, Chinatsu begins living with Keigo and enjoys happy days together. However, his love gradually becomes something she cannot escape. Eventually, Chinatsu becomes a victim of Keigo's obsessive affection, leading to a tragic ending. The shifting emotions of innocence, love, and control throughout this process form the core appeal of this work.