Momoyo is a daughter of Yae and Genta. Due to poverty, Yae and Genta decide to give Momoyo to the Sakurakoujis as an adopted child. Even though Momoyo is loved by her foster parents and looks very happy, her grandfather wouldn't accept her as his granddaughter. Momoyo meets her cousin, Reiko. Reiko says there's a secret about Momoyo.