A Hellish Arrangement

Demon King Kashuriel has declared he'll marry the human princess, and he's come to take her home. But the princess who matches him blow for blow is actually her bodyguard in disguise: Berik Rednile, the greatest swordsman on the continent. Smitten at first sight, the Demon King changes his mind and says he'll marry Berik instead. To keep peace in the human world, Berik follows him to the demon realm, where everything is new to him. Now the unshakableknight faces the biggest challenge of his life...and it's a big one.

(Source: Lezhin Entertainment)