Yongsa Chullyeon Mawang Yeonchul

The Demon King Krad, is a threat to the Dominion Continent. Dreaming of a decisive battle with a worthy rival, he sits in the Demon King's castle, waiting patiently for warriors. Fatigued by thousands of years of waiting for a worthy opponent, Krad stumbles upon human poo culture. But what genre is the favorite of this absolute being, possessing the power to destroy the world...?

(Source: Naver, translated)