The Fifth Post Office Envoy

Chase Hale becomes a Postal Envoy to raise funds for his sister's surgery, learning that delivering mail is a task to seal Abyssal Beasts. Seal Stamps can be exchanged for power, and every mission is dangerous. He joins the Night Watchers, uncovers the secrets of the Fifth Post Office, confronts dark forces, and launches the ultimate battle to determine the fate of humanity, to protect the human world.