What's Wrong with a Hero's Second Life as the Demon King's Disciple?

For his mediocre performance, Les Field has been dubbed "Useless the Second" and "the Heroic Mediocrity."

Living with resentment in the shadow of his father, he encounters the spirit of a Demon King who died twenty years ago in a secret room of the family estate.

"Lad, I have a grudge against your father..."

"So... let me teach you how to defeat the one you think you can never surpass."

And so the former Demon King became the son of his enemy's mentor.

The mediocre second-generation successor to one of the Seven Heroes now embarks on a journey that will make the world tremble.