This has many flaws, but it's an ok read... if you enjoy overpowered characters, evil x good stories, no hard work, and slice of life, this is a recommended manga.
If you did find the "being able to live longer than others" topic interesting, try reading "Time enough for love" by Robert A. Heinlein. I remember it from my highschool years, and while it may not have "magic", just "science fiction technology", the MC is not overpowered, struggles to live (in mid of war/colonization, poverty, or just trying to find a reason to not kill himself), and his long life has political implications... that book would actually make you feel a myriad of emotions, be it angst, happiness, sorrow, even ---...
I think my problem with this manga is how you can't relate to any character at all, they're all flat... other thing would be that the author tends to insert events/dialogues out of nowhere, but I do think it's because he's tring to pace the story, without having much sustance (yet)... the whole demons are evil makes no sense to me,but who knows, maybe there may be some future development... all in all, other than toilet reading, there's not much to see here...