tl;dr: A manga centered around betrayal that takes too long for things to start clicking and feeling adequately fleshed out but does well when they finally do.

If there was one word I would use to describe the core of this manga, it would be betrayal. The vast majority of the plot centers around someone betraying someone else or it being unclear who is loyal to whom. This manifests in lots of different ways, such as betraying people during key fights, leaking information, or stealing relics. There's action and some other strategizing as well, but at its core, betrayal and alliances is what it feels like the crusades here are all about. And to a certain degree it works in adding a good amount of suspense and intrigue. The issue with this however, is that for the vast majority of the manga, this involves characters with undefined backgrounds betraying each other due to unclear motivations as a part of an ambiguous game. The twists just on their own are interesting at first, but after it happens for the tenth time and we still have no clue as to the foundations for why all of this is occurring in the first place, it feels like there's something missing, and it starts getting kind of old. Also, if it wasn't clear, there is little fleshing out of characters for most of the manga, wherein because motivations and backgrounds aren't made clear until the very end, no development or relationship development really occurs, and though the character set is reasonably interesting and a few are pretty easy to get attached to, for the most part they feel pretty flat. The lack of clear explanation for the crusades themselves also makes a lot of the twists involving aspects related to that lack impact. Still, as it approaches the end, there's a really fast paced rush where everything gets adequately revealed, characters goals and backgrounds are made clear, the way the systems of the crusade work feels complete, the plot starts moving really fast into a solid climax, leading into ending on a pretty good note that I'm satisfied with. The art was decent, but it basically felt like CLAMP lite, though even more shoujo looking, which felt limiting at times.