Don't let the first volume deceive you--this manhwa is actually incredibly messed up. XD Like the first commenter said in his/her title,"sinister" describes it really well, but it's not a horror manhwa; at least, not exactly. Judging from the raws, it seems more of a tragedy, though I don't understand Korean, so I can't be sure. But there's a lot going on behind this asides from "weird Demon King" and "Asrella, the mage-girl." (And Elihue... btw, what is up with CPM's weird spelling of his name, anyway? >>;😉
It's not a typical shoujo manhwa where everything is set and predictable, defined in overdone, cliched stereotypes--the plot keeps twisting and writhing around (I should say that the timeline does, too..). This overarching sense of angst/tragedy on top of the strange and intriguing storyline is part of the reason why I really like this manhwa (though I have this unsettling feeling of DOOM whenever I read it.. XD;😉
The character designs are really good; this manhwa-ga actually put thought into what an immortal being would be like, and it shows. Asarella is intriguing as well, and the drawing in general is really good, with masterful usage of tones and an interesting style that's an aesthetically pleasing mix between shoujo and shounen. The universe beyond the plot is rather complex, leading a definitely fantastical air to it, but thankfully the manhwa-ga doesn't "tell" too much (unlike CLAMP, with truthfully always puts me off their series..).
Masca is worth reading, if only to check out the Demon Lord (who is definitely one of the hottest things I've seen on paper). But I think that the plot will definitely suck you in, as it did me. ^^