"I have an unusual attachment to my older brother." Hayato and Yuki are two high school students who are also stepbrothers. Although they share a mother, she works in a bar and moved in to live with her lover, leaving the two brothers to rely on each other. However, older brother Yuki who was always concerned about Hayato suddenly starts avoiding him. Why? Loneliness and doubts will eventually turned into an abnormal obsession! This is a brother's criminal grade love that went overboard!