Kenji, the quiet and withdrawn middle son of three brothers, is left living alone with his mother Rieko after his older brother moves out for work, his younger brother enters a boarding school, and his father takes a distant assignment. The once-busy house falls silent, leaving Rieko with a deep sense of loss. Hurt that she seems to care only about his brothers, Kenji becomes determined to claim all of his mother’s affection for himself, pushing their life together across a forbidden boundary.