Meirin stumbles by chance upon her brother Koumi walking with a girl. The girl is said to be Koumi's girlfriend, Azusa. The Kanzaki family immediately decides to invite Azusa to a party. Soon enough, the members of the Kanzaki family have become friends with the beautiful and friendly Azusa, including Meirin. However, when he's left alone with Azusa, Koumi seems to be acting strangely...