This is the third volume of the I'm Quitting Heroing: Next Gig Is at the Demon Queen's Castle manga adaptation.
Synopsis[]
To protect the world, destroy the world? Really, Hero, quit! The strongest man who had been defending people for 3,000 years was eventually not needed by humans and was released from duty. He decided to hand over the "Philosopher's Stone" to the Demon King in order to truly leave the brave, but it was the beginning of the worst battle.