Koshiro remembers the birth of his sister and their life together before their parent's divorce. Although they were too far apart in age to understand each other, they felt a vague sense of affection. In the present, Koshiro goes to see his mother for the first time in many years. She tells him how much Nanoka looked up to her big brother and tells him to be a good big brother to her. On the ride back, he remembers an incident when baby Nanoka gave him a glass of mud and he ended up keeping it because it made her so happy. He resolves to be a good big brother to her.
Koshiro recuerda el nacimiento de su hermana y su vida juntos antes del divorcio de sus padres. Aunque estaban demasiado separados en edad para entenderse, sentían una vaga sensación de afecto. En el presente, Koshiro va a ver a su madre por primera vez en muchos años. Ella le dice cuánto admiraba Nanoka a su hermano mayor y le dice que sea un buen hermano mayor para ella. En el viaje de regreso, recuerda un incidente cuando el bebé Nanoka le dio un vaso de barro y terminó quedándose con él porque la hacía muy feliz. Decide ser un buen hermano mayor para ella.
