Helck

After a human hero kills the Demon King, the demon realm needs a new ruler and organizes a tournament to choose his successor. Vamirio, one of the Four Heavenly Kings, oversees the contest and immediately distrusts one impossible participant: Helck, an overwhelmingly powerful human hero who cheerfully claims to hate humanity and wants to become the next Demon King.

Vamirio repeatedly tries to expose his supposed scheme and eliminate him, but Helck keeps winning and becoming more popular. Meanwhile, stranger reports arrive from the human lands: entire towns have emptied, and winged soldiers now appear where their people once lived. What begins as a bizarre tournament comedy slowly reveals a crisis threatening both realms. To learn the truth, Vamirio is eventually forced to travel beside the very man she considered the most dangerous contestant in the competition.