Yoko is a serious girl who puts all her effort into her work. Recently, she has been bumping into her neighbor, Kaiji, a frivolous looking guy, and they have started exchanging greetings. In fact, Kaiji has noticed that Yoko is being stalked by a suspicious man and has been worried about her. So, until she is caught by the police, Kaiji hides her at his house, but...!?