Mirei is the eldest daughter of the Kazuha family, who was raised with a strict education. She had her first sexual experience at the age of 1●, and her sexuality blossomed thanks to a man she met at a university group date. However, she broke up with that boyfriend at the same time that her father's business debts increased, and Mirei was heartbroken. Kazuha's family was on the verge of bankruptcy, but then Aihara, a land tycoon, offered to lend her money. In return, Mirei would marry Aihara's son, who would be the heir to the Aihara family. Mirei agreed, and headed to the old mansion with the head of the Aihara family for a certain ceremony...