Tokyo Zombie - Yusaku Hanakuma

Horror-comedy manga about two blue-collar factory workers and jiu-jitsu experts who deal with a zombie uprising in Tokyo. Fujio and Mitsuo accidentally kill their overbearing boss and bury him in a man-made mountain, where tons of rotting garbage contaminated with industrial waste transforms the bodies of the dead into ravenous, flesh-eating zombies. A few years later, post-apocalyptic Tokyo has become a feudalistic society in which the rich make slaves fight zombies in gladiator death matches. Fujio and Mitsuo meet again...