"I'm going to make you a substitute." I saw my Prince Charming for the first time in ten years. He calls my long-lost twin sister's name while making love to me... Left with no one to turn to, Iroha is taken to a house and the owner of the house turns out to be the boy she met when she was a little girl! But what Arashi wants is her sister, and he uses Iroha to satisfy his desires... "If you want me to like you, prove it." Iroha doesn't like seeing Arashi sad, so she has sex with him every day, hoping that it'll make him smile... One day, Iroha finds herself inside the room she's not supposed to enter...! What's going on in this place...!?