Gangho Apocalpyse

For destroying the treasured library of the Hwasan Sect, Cheong-Su was sentenced to be imprisoned in Hwasan's penitentiary for three years. But when his punishment ends, he discovers that his sect has been overrun and destroyed by undead monsters called sigwi. With no way of knowing if anyone else survived, Cheong-Su is left to fend for himself until he runs into a stranger who may have the answers he needs. The question is whether he'll be strong enough to face the truth...

(Source: Tapas, edited)