Slave Widow (1967)

After her husband's suicide, young and beautiful Mitsuko Fuji feels alone and helpless -- until one of her husband's major creditors, Mr. Kito, offers a sympathetic ear and a cancellation of all debts. However, Mitsuko soon learns that Kito's intentions are anything but pure, as she's forced to become his personal concubine. Her only, improbable hope for redemption lies with her one true admirer: Kito's very own son.