Kenji, a husband who is inflated with expectations and anxiety, is about to give birth to his wife, Honoka. One day, Mako, Kenji's sister-in-law, came to help with the housework. Kenji becomes a melody to Mako who is cute, nice buddy, and gentle to the bonus. Kenji, who has been accumulating enough to become a gold ball bun for a while after a couple's life with Honoka, can not stand it at last.