Kenji, the easygoing middle son of three brothers, is left living alone with his mother when his older brother moves out for work, his younger brother enters a boarding school, and his father takes an assignment away from home. The suddenly silent house leaves his mother aching with loneliness. Hurt that she seems preoccupied with his brothers, Kenji tries to claim all of her affection for himself, drawing mother and adult son into an incestuous relationship.