Grandpa and Grandma Turn Young Again
Grandpa and Grandma and the Sports Festival
S1 E1:
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!