Momoyo is a daughter of Yae and Genta. Because of poverty, Yae and Genta decide to give Momoyo to the Sakurakoujis as an adopted child. Eight years later, Genta dies in a storm and Yae moves to Tokyo to become a housekeeper. When she looks after Midori, who has a heart disease, she meets Momoyo. After Midori dies from heart attack, Momoyo takes Yae to the Sakurakoujis. 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.