King of Hell, Volumes 1-3 by Ra In-Soo

Imagine the greatest swordman of all time is dead, trapped in the body of a boy, and hunting down escaped monsters from the underworld for the King of Hell.  By the way, the King of Hell is a cranky old man who like to ridicule and throw things when he doesn't get his way, and the swordsman has the maturity of Naruto.  That is King of Hell in a nutshell.  One part fighting, one part comedy, with just enough plot to keep things moving and interesting.

All of these are good things. King of Hell has the whimsy you expect from Dragon Ball, the kind of jokes you see in Naruto, and the fighting style reminds me of old kung-fu movies where everyone fought while flying on wires.  In other words, it's really entertaining.  Majeh, the swordsman, switches from acting like he's a teenager when he's not fighting to a seasoned fighter when he is in battle without it seeming awkward.  It's clearly still the same character.  He's also like an evil, but good-hearted imp.  He helps people, but messes with them while he does it.  When Majeh finds out that a fellow dead soul is spying on him for the King of Hell, he forces the soul to serve him as a slave and makes him dance and sing for him.  If you are looking for something that feels like Naruto from the humor to the fighting, you want this manga.