Yumi, a wife who is troubled by a sexless marriage with her husband. One day, after finding out that her husband was cheating on her, she decided to start "improving her physical condition through yoga = mankatsu" on the advice of a friend who had the same problem. As she continued, her body began to change, and her husband also became more proactive in their nighttime activities... Just when she thought she had finally resolved her long-awaited sexless marriage, her nephew became aroused by the effects of mankatsu! Yumi's body became so sensitive that she couldn't resist her nephew, and he even taught her her first squirting orgasm...