The Oosaki family has welcomed several homestay students and now, they are going to accept a long-term one. When the student comes however, it's a tall and muscular man. But in contrast with his scary appearance, he seems to be a polite and earnest person. Suddenly, the husband is called to go on a business trip​, leaving his wife, daughter and the young man alone at home. Meanwhile, the man's sexual urges gradually increase and then finally...