Fumino Ishikawa enjoys a night off after a long time. When her husband's colleague visits, she asks him about the secret to a happy marriage, but he dodges the question and she gains no useful insight. As she politely sees off the drunken guest, she can't help but notice the prominent bulge in his pants. Mesmerized by its impressive size, she throws caution to the wind and gives in to temptation—completely ignoring her sleeping husband. Turns out, the real secret to marital bliss is a big cock after all!