Mirei, the eldest daughter of the Kazuha family who received a strict education.She had her first experience at the age of 17, and her sexuality was blooming with a man she met at a university joint party.However, Mirei breaks up with her lover at the same time as her father's business debt, and Mirei is heartbroken.Kazuha's house is on the verge of bankruptcy, but Aihara, a land nominee, raises the issue of financing.In return, Mirei will be married off to her son, the heir to the Aihara family.Mirei agrees, and she goes to an old mansion with the head of the Aihara family for a certain ceremony...