Grandpa and Grandma Turn Young Again

Shouzou and Ine, an old married couple, are known to everyone as a pair of lovebirds. One day, they wake up to find they look like their younger selves! When Mino, their granddaughter, sees them, she's shocked by their transformation, and she's not alone!

Shouzou and Ine often have visitors dropping by. One day, their granddaughter, Shiori, comes to their house after a fight with her father, Takahiro. He's a doctor. Shiori aims to follow in his footsteps, but she's worried about her grades and friendships.

Ever since Shouzou and Ine turned young again, they've had dreams of a mysterious hourglass. One night, Shouzou has the dream again and something unexpected happens. The next morning, when he wakes, his body has returned to that of an old man.

Ine's memories have turned young again. She is now who she was before she met Shouzou. Even amidst her confusion at seemingly having traveled into the future, she is curious as to why she married Shouzou and offers him a certain suggestion.

As their long-awaited honeymoon approaches, Shouzou and Ine plan the details of their trip. They recruit Shouta to be their guide, and Mino decides to go with them, too. Once they arrive in Tokyo, Shouzou and Ine go to see their daughter Akemi.