This is a great read. I'd love an anime or VN adaptation, though I'm not sure how well that would work out.
Spoiler for vol 4:
It looks like Kazuki's abnormality is that he seems to be the only person content with his own life. It makes sense why he's someone that can trample on someone's wishes, or grant them -- he has no wish for himself... or at least he didn't until after the game. With Daiya manipulating Kazuki's desire, Kazuki now has a concrete desire (to protect Maria). Having a concrete desire is why 0 was supposed to lose interest in Kazuki. It's a shame though, because I believe Kazuki was at his best when he had something he wanted in Volume 4 and proceeded to outsmart Yuuri and Iroha.
Aside from the romantic pairing, Maria also sounds like Kazuki's foil to me. Her personality, her motivations, and her "wish" all contrast with his. Her "Flawed Bliss" is a neverending wishbox. In order for her wish to be complete, she has to grant everyone else's wishes and make everyone happy. Of course, that is an impossibility. Thus, she will never be satisfied, and her box will never disappear. Because this desire is the polar opposite of Kazuki's, even 0 has a distaste for her.
Right now, hints of the Kazuki x Maria pairing are all over the place, but both of them are a bit misguided. Maria obviously needs to stop being Archer and become happy with her own life. Kazuki obviously wants Maria to be part of his life, but as he is right now he believes Maria opposes his everyday life. When Maria stops being atruistic and Kazuki sees her as part of his nromal life, not an anomaly, I'm sure there will be a happy ending.
Also, I'm a big fan of Otonashi's messy hair.
As for the artwork in general, the style looks appearing enough, but I can't help but think that it doesn't fit the characters in certain areas. For example, I'm pretty sure Kokone has an ample chest she brags about once, but the single illustration of her doesn't show that. In fact... everyone looks like they have the same physique.