I'm not sure if the word 'manga' is strictly appropriate since, from the few bits of original text that haven't been removed, I'm guessing it is Korean in origin.
My best guess is that Kara read AngelSanctuary, loved the idea and the art but thought the story was a bit too much on the dark side and decided to do her own version ^^;;;
It is very pretty. Perhaps not quite to the standard of AngelSanctuary but still very nice. The basic plot is basically just that a new Demon Lord (young cute, rather dim, bishy) is being trained for the 'job' by his tutor/guardian Eclipse (tall handsome stylish bishy).
Ah yes, did I mention Kara likes Shounen-Ai? :) Don't worry, nothing graphic. So far it's about YamiNoMatsuei level or less.
Anyway, you don't really have to worry about it if you don't want to since Raenef (Demon Lord) is this year's entry for the "ThatCannotBeMale" award.