In a world governed by 72 gods, there is one man known by the people as the "Sword Saint," Nebi Cerberus. However, he was banished from the world by Lucy, the first goddess of beginnings. Nebi's near-death state is found by a girl named Asta, who calls herself the 73rd god of decay. As a sword of revenge against Lucy, she bestows upon Nebi her protection and saves his life. However, the one who rises up is a dangerous man who could be described as addicted to leveling... A leveling-hungry useless dog and a god whose existence has been forgotten. This is the beginning of the unorthodox tale of revenge between these two...or rather, the leveling-up process.