The Arimura couple had a very happy life in a luxury apartment until their black neighbor Steve moved in upstairs. After a chance meeting outside and getting to know each other pleasantly, Steve introduced Arimura to an English communication course at home for beginners that he taught himself. She went home to ask for her husband's permission, and he quickly agreed because he found Steve to be a friendly foreigner worth trusting. He had no idea that this was the moment his wife, whom he had lived with for many years, would officially belong to another man. From then on, Steve frequently visited their home, but he always focused on Arimura's fair body instead of teaching her. One time, while drinking at their house, using drunkenness as an excuse, Steve took possession of Arimura's body while her husband was completely intoxicated. Arimura seems to resist at first, but upon seeing the huge penis of the black man, she immediately turns around, only knowing how to lie down and be satisfied. Since then, every class has been an affair behind the back of the unfortunate husband.