Akai kinryōku: haado koa no yoru (1986)

Keigo, whose mistress is Michiko, 22, is unhappy with meetings three days a week and eventually brings Michiko to his home. The desire for betrayal that was sleeping in his wife Satomi finally exploded due to her husband's abnormality, burst out like a dam, and finally turned into a "double marriage" strategy, far beyond her husband's infidelity...