The story is about Yanagiba Masahiko, nicknamed Giba, whose mother died while he was in kindergarten. His father being regularly away on business, Masahiko often spent his time alone longing for a family like those he had seen on television. A month after his father died in a traffic accident, a relative came to his door. Masahiko mistook her for his mother, but the relative told him that he was mistaken for she was his aunt, Wakanae Yukari, his mother's little brother's wife. Masahiko’s mother had broken all ties with her brother. Yukari wanted him to come and live with her family as Masahiko went to the university.
Yukari invited him to come that night to meet the family before he decided. He met the daughter, Shion, on the way, and mistook her for a neighbor. Masahiko asked questions about the Wakanae family, because he was worried as to why his mother had broken ties with her brother. When they arrived at the house, he met his Uncle Sora and discovered that the girl directing him was really his cousin. He realized that this was her 16th birthday, and the family would be having a party together. A birthday party was something that Masahiko had always desired as his father just left presents for him, but never celebrated his birthday with him. His worried that the Wakanae were yakuza seemed dispelled by the warm home atmosphere, yet still he wondered why his mother disowned her brother, Sora, who seemed to be a kind and good natured husband and father.
Shion, who was drinking quite a bit, yelled down from her balcony that her father should hurry and tell Masahiko the "truth." She dumped a tub of water onto her father, yelling to Masahiko to hurry and help change the clothing of her drunken father or he would catch a cold. As Masahiko was helping his drunken uncle take off his shirt, he discovered that his uncle has breasts and was in fact a woman. The drunken and stunned Masahiko stumbled around falling into the bathroom where his aunt was showering. He discovered that his aunt was a man and was in fact the uncle, his mother's younger brother, which his mother's family had disowned many years before.
So began Masahiko’s strange new family life.