With his wife Honoka due to give birth soon, Kenji is filled with both excitement and anxiety. One day, Kenji's sister-in-law Mako comes to help with the housework. Kenji is smitten by Mako, who is cute, has a nice body, and is also very kind. Kenji's balls are filled to bursting with pent-up desire, but he can't hold back any longer...