Nidome no Jinsei: Animator

Tada Ayumu is a completely normal 58-year-old salaryman. His daughter, who loves anime, is about to get married to a man who also likes anime, and Ayumu feels distant from them because he has no interest in the medium. Suddenly, he time slips 40 years into the past, back to his 3rd year of high school! One of his classmates happens to become a famous animator in the future, and so Ayumu begins animating with him.

(Source: Shonen Gahosha, translated)