ナインピークス　NINE PEAKS

Gaku Mashio, a tough and rebellious high school freshman, lives with his father, Harumi, in a small coastal town, often clashing with local delinquents despite Harumi's disapproval. After a tragic accident claims Harumi's life, Gaku, devastated, goes fishing—a cherished activity they once shared—and falls into the sea, only to awaken 22 years in the past. Rescued by a young Harumi, now his own age, Gaku finds himself in a town overrun by gangs, where he must navigate the challenges of the past while forging a bond with his father as peers. Together, they aim to conquer the town's delinquent hierarchy, blending intense action with heartfelt father-son dynamics. (Unreviewed summary by Grok 2)