Shadow of Deception (内海の輪), Ko ichi Saito , 1971

It was five years ago when Minako spent a night with Sozo, the younger brother of her exhusband. She now lives in a local town with a rich old man who owns a dry goods store. Minako travels to Tokyo on business every three months, during which time she continues to meet Sozo, who has married the daughter of his respected teacher.