Every 300 years, the greatest sinner on Earth is chosen from Hell and given one final chance in another world. Ogon, a Hell guardian appointed by the gods to oversee the sinner’s transmigration ritual, has his boring life in hell cut short when his soul is mysteriously swapped with the sinner’s. Now trapped in the body of a dead mercenary, Ogon finds himself in a strange land of humans, war, and corruption, forced to navigate a world ruled by morals he never possessed. Why did his soul get swapped with the sinner’s? How could he possibly go back? A dark fantasy isekai journey begins.