Tsumugi is the fiance of Yuu, the eldest son of a rice cracker shop that has been in business for 120 years. To marry into a distinguished and prestigious family, she must get the approval of her strict father. Beautiful, brave and pure, Tsumugi is the ideal bride... or so she should be... But in fact, she has another face as the legendary prostitute "Himeka-chan", who has been the No. 1 prostitute for two consecutive years. This must never be revealed. She appeals to her chastity and does not allow sex until marriage, even to the brink... However, Himeka-chan (Tsumugi), who has been through many battles, unconsciously shows off her "amazing technique". Yuzuru has doubts about Tsumugi. Then, her father asks a detective to look into Mahiro's background... What will happen? ?