Seiji was born as the second son of three brothers. From her mother Reika's perspective, she seemed like a child who didn't need much help... One spring, my older brother got a job and lived alone, and my younger brother enrolled in a boarding school. Seiji and Reika's life changed rapidly as their father moved away from home, and Seiji and Reika started living as a mother and son. The once lively house suddenly becomes quiet, and Reika feels a sense of loss. Seeing his mother in such a state, Seiji feels regret and emptiness, and tries to regain her mother's love, which he was unable to monopolize until now.