botan, a 2nd year in high school from the city of Kyoto lives a relatively normal life with his parents and older sister, life is good he cant complain all until a young girl no more then a year younger than himself comes up to him claiming to be his younger sister, this plunging him into a downward spiral of paranoia and fear. botan is aware of his parentage knowing he is adopted, knowing he was abandoned, he's lived his life not having a desire to meet his biological parents but know they somehow forced their way into it much to botan's despair.