Demon King Owes 66 Trillion Debt so He is Forced to Become An Ad

The strongest demon king, Merlin, falls into a massive debt and is forced to earn money in the human world. He encounters Alice, a hero, and faces various challenges, including battling goblins and a powerful goblin king. As they navigate their tumultuous relationship, Merlin aims to become an adventurer while Alice seeks revenge and redemption.