I moved to Tokyo for a new job, excited about living alone for the first time. Then moans that sounded like porn blasted through the wall all night and kept me awake. The next morning, I confronted the man leaving the apartment next door, only for a beautiful woman to emerge behind him. The sounds I had mistaken for porn belonged to his wife—and while her husband was away, the sexually frustrated neighbor seduced me into a sweaty week of nonstop sex.