This Brave Man Is a Former Demon King.

The Demon King, once hailed as the "strongest" for ages, grew weary of his existence after repelling countless heroes who challenged him. Finally, he plunged a sword into his own heart—only to wake up a thousand years later, reincarnated as a human baby! Now reborn as Zeon, the former Demon King fully intends to enjoy his new life as a human peasant. However, through a strange turn of events, he ends up being officially recognized as the Hero of this era?! The tale of a reincarnated Demon King’s unrivaled Hero saga begins!!