The Ossan Newbie Adventurer, Trained to Death by the Most Powerful Party, Became Invincible

TMDB score: 8.0/10

Normally, people choose to become adventurers in their teens. At 30 years old, Rick Gladiator bucks the trend by leaving his job as a guild clerk to become an adventurer. He begins as a novice F-rank with the fighting strength of an S-rank. After two years of brutal training with the continent’s strongest party, Orichalcum Fist, Rick will defeat anyone who underestimates him!

Selected season 1, episode 1.