Four years after getting married, Taro and his wife Naoko were looking at real estate in Tokyo with Naoko's mother Shizuka in order to buy a house. They finally found a suitable property, but the price was high, which worried Taro. "If that's the case, I'll pay the down payment, so how about we live together?" Shizuka suggested, and Taro and his wife and Shizuka decided to live together as two generations. And so they began living together with his wife's mother. But there was an unexpected event that even Taro hadn't expected.