After losing his parents, Masahiko Yanagiba obeyed his mother's testament and went to live with his maternal uncle's family, the Wakanaes. Even though their hospitality was welcoming, Masahiko ultimately discovered why his other relatives avoided the Wakanaes: his "uncle" is female and his "aunt" is male. To his surprise, the couple adopted opposite gender appearances, making it difficult for Masahiko to determine if his charming cousin, Shion Wakanae, is male or female.