Iroha comes to support her emotionally fragile pregnant daughter, and her devoted help eases the wife's stress. But for the husband, who has been forbidden even to masturbate, his alluring mother-in-law is a constant temptation. One day he secretly watches her bathe, too captivated by her body to notice she has caught him. Seeing how desperate he has become, Iroha makes a forbidden offer to relieve him by hand, opening the way to repeated breeding sex behind his pregnant wife's back.