Masahiko, the president of a large company, was approached by Mukai, a subcontractor, for advice. To prevent bankruptcy, he asked for financial assistance, but Mukai refused. Instead, he proposed a marriage between his daughter Ai and his only son, Naoto. Having shown an interest in Ai for some time, Masahiko agreed and at the same time came up with a plan. Until the wedding, Masahiko forbade premarital sex, pushing Ai's sexual desire to the limit. Then, after sending Naoto and his wife away for five days on the pretext of a business trip, Masahiko was left alone with Ai, and he carried out the training plan he had dreamed of for many years...