The Returner's Road to Retirement

After two decades of battling extradimensional monsters and protecting the world, Dae-in Lim is finally ready to retire and enjoy a peaceful life. However, the morning after his retirement party, he wakes up to find himself back in time... before he even gained his powers. Armed with knowledge of the future, Dae-in is determined to secure his fortune and retire again, but this time within three years.

(Source: Webtoon Entertainment)