Nikola, a martial artist who was a member of the Hero's Party, is betrayed by the Heroes he had believed to be his comrades.

Scarred by the trauma, he abandons his former life and dedicates himself to solitary training in the forest, ultimately becoming the strongest human in the world. Meanwhile, having lost Nikola, the Heroes see their reputation plummet and are forced to live a miserable existence.

Will his newfound, immense power be directed towards revenge? Or will he overcome the trauma of betrayal and once again live as a member of the Hero's Party?

The story of the strongest martial artist, torn between passionate recruitment offers from both demons and humans, finally begins.

Published as a book by Shueisha. A manga adaptation is also running on Manga UP.

Also serialized on Kakuyomu.