When his sister escapes home after discovering a painful truth, Marl Stimson makes a pact with a god, seeking to rid himself of his problems, but the god gave him the power needed to solve them. This agreement leads him to become a champion, which he sees as heroism, but life in that state brings him no satisfaction. Through unexpected circumstances, Marl loses the granted power and is transported to an unknown universe, where he is mistaken for a strange term called "sold one."
In this new realm, magic, known as kio, is a reality, and Marl faces decisions that put his morality at stake: accept money and live leaving his past behind or train to become stronger and protect his loved ones. The god who granted him his power contacts Marl again, revealing his sister's location, giving him new motivation.
Determined to face his mistakes and give up a life away from his past, Marl commits to becoming the strongest warrior in this medieval and fantastic world. Under Valdor's tutorship and Finn's support, he begins to explore his new environment, forming meaningful relationships and acquiring the necessary power to protect those he loves from the imminent threat of the Infinity warriors. Promising not to make the same mistakes, thus beginning his legend. The legend of Marl.