I'm a Coward in the World of the Dead

My family's ancestral motto: I would rather provoke the King of Hell than touch a living corpse. Three years ago, Master broke his precepts for a mysterious business and disappeared from the world. In order to find him, I stepped into the taboo, only to find that the "living corpse" was actually the key, which could open the "underworld" built by resentment - a forbidden land with rules for killing and unlimited movement! With no magic power and no knowledge of spiritual practice, I relied on my ancestral corpse exorcism skills and my ultimate anatomy reasoning to break into the weird replicas consisting of mass murders and human sacrifices. They rely on magic weapons, I rely on brains. Peeling away the layers of bones, I vow to dig out the truth from this forbidden ruin!