I Am the Public Enemy of All Humanity

A High-Martial World: Martial artists prize vital blood and are ranked in nine grades. Above the ninth grade are Grandmasters, Great Grandmasters, and Martial Sages.

The zombies are not traditional zombies, but "Blood Fiends": they feed on other people's vital blood. Those bitten do not die, but gradually lose their minds until they eventually become one of them.

The Forbidden Zone lies at the deepest point in the world. It has been sealed by the major factions working together, and legend says it holds an ancient demon.