On his fourteenth birthday, Daisuke Niwa comes down with a condition that has plagued men in his family for centuries, causing him to turn into the phantom thief Dark Mousy every time he sees his crush, Risa, and back into Daisuke when he sees Risa's twin, Riku, but in the midst of all the craziness, Daisuke must find a way to get Risa to fall in love with him and cure his condition for good.
