I'm Ten, But I'm Your Grandpa

In 1976, Ryan Brooks, the nine-time world Go champion, took his wife and daughter to the countryside. While foraging for wild vegetables, he stumbled upon a game between Arcturus Valeen and Fenric Moonholt. Mesmerized, Ryan stepped in to play a move for Fenric, only to discover upon the game's end that 49 years had passed in the mortal world. To make amends for the lost time, Fenric gifted him a mythical peach of immortality, but its potent magic backfired, reversing Ryan's age and transforming him into a ten-year-old child.