Immortal Regis by Ga On Bi & JUDER
I'm guessing it's a new manga since there are only 13 episodes that I can find...even though I think I saw something about 5 volumes already being out. If anyone does know where some more translated scans, I think that's what they're called, please tell me.
Anyway, I really actually like this...guess I'll give you a description which I got from onemanga...
Title: Immortal Regis
Categories: action, manhwa(what the heck is this??:blink), shounen, supernatural
Summary:One day, suddenly... a night where the moon shines like never before, a boy meets the otherworldly Serin, a denizen of Chaos, only to die and become the undead. Now immortal, he can no longer exist with humans due to an ancient law... A tale of revelations that begins as he returns to Chaos, the start of a new adventure!