And by characters I mean Seimei, Masahiro, and Touda. The characters themselves are what really carry the anime. It doesn't look like much at first, the character designs for some of the shikigami are kinda generic and almost all of the human character's faces and designs look the same. It can look decent in places where its supposed to but it also seems like they really had to stick in weird long pauses so they wouldnt have to animate some scenes lol. You can tell that they really had to stretch that budget to make it last 24 episodes. SPOLERS AHEAD Edit: More indpeth about the story and anime tho, at times the animation can look kinda jank. I just wish that some of the other familiars could have had more fleshed out backgrounds but theres only 24 episodes and a crap ton of plot to cover, so thats understandable. Its sweet and heart wrenching and all of the characters are interesting. I'd recommend watching the anime because it really is a great story. I'll admit tho, the art is really cute and resembles the art used in the light novel's cover. Its less of a manga in its own right and more like a glorified doujinshi. But back to the review, the manga is a super incomplete quickie adapation of the anime. I've been looking for up to date translations of the light novel where the anime left off so if anyone knows a site that has them, hit me up plz.
Anyway, this manga is based off the anime which is actually based off of a light novel series (which is surprisingly still continuing based on the wikipedia page o.o).
Its really old tho, it was made back in 2006 and although the budget was probably sizable back then, today the animation has not aged all that well.