Shinmai Ossan Boukensha, Saikyou Party ni Shinu hodo Kitaerarete Muteki ni Naru.  

It is widely believed that it's best for individuals to start their journey as an adventurer when they are young. This is because the magical power that forms the foundation of an adventurer's strength will not fully develop if it isn't trained during this time. However, there is a man named Rick Gladiator who became an adventurer later in life and still possesses the combat power of an S-rank adventurer, which is the highest rank achievable worldwide. Despite his late start, Rick has had an extraordinary existence with the legendary Orihalcon Fist, a group of the continent's strongest adventurers. They have faced challenges ranging from dragons to vampires and have emerged victorious thanks to Rick's formidable fighting skills, which were honed by mentors who were themselves monsters. As a result, he has defeated numerous elite adventurers who underestimated him.

Shinmai Ossan Boukensha, Saikyou Party ni Shinu hodo Kitaerarete Muteki ni Naru. began as web novel. The first offical volume was published on December 22, 2018 by Hobby Japan under the HJ Novels label.