Makoto, who moved to Tokyo for work, was attracted to the mature sex appeal of his next door neighbor, Eriko, a married woman. One night, he heard a seductive voice coming from next door and followed it to the wall, where he discovered a mysterious hole. He tried to keep quiet and looked through the hole, only to find Eriko's lewd figure in full view... From that day on, Makoto became obsessed with the peephole, and he began to satisfy his desires by not only peeking but also inserting his penis into the hole. Then he felt as if he was really having sex with Eriko...