Yu Shirakawa has been living with his grandparents, but now he is going to live with his mother after ten years of separation. Her new husband, his stepfather, has three very beautiful daughters who are now his stepsisters. These girlsKyoko, Ryoko, and Anzu Shirakawaare waiting for him, welcome him, and let him use the room their father uses for his archaeological finds. In the room, Yu finds a cursed jar which, unless he collects woman's "love juice" within the period of time, will cast a terrible curse on him.