- Niwa Daisuke is your average teenager, until his fourteenth birthday. He tries to declare his love to the girl of his dreams, but fails. Suddenly, whenever he thinks about this girl he turns into the legendary phantom thief known as Dark Mousy. Daisuke's mother, very much aware of this, makes him turn into Dark and steal valuable works of art for a purpose unkown to Daisuke. As the story unfolds, he learns why, and about his classmate who seems to have the same ability.Niwa Daisuke, a 14 year old boy who spills his love to Harada Risa. When rejected, his DNA changes and is mixed with the ancient phantom thief Dark. As his life and Dark's intertwine, he is forced to steal the artwork of the Hikari. As time passes, mysteries are uncovered of Dark's past, the ancient battle, and the heart of Daisuke.