Also known as Urakata!! Manga by Bisco Hatori. Final Volume.
The story follows Ranmaru, a super-negative college student. It's two months into Ranmaru's college career, and if he's learned one thing, it’s that he’s really uncomfortable around other people. But when he stumbles into a zombie mob attack, he’s totally forced out of his comfort zone! Of course it's just a movie shoot, but when he wakes up from his ignoble faint, he's been whisked away behind the scenes with the Art Squad! Could this group of weirdos be what Ranmaru's been looking for all his life?!