As an animal trainer who can communicate with sea creatures, Castiel's lifelong dream is to own a boat of his own. However, the inheritance he received was the "Deathrattle", a ghost ship that was "cursed by the River Styx" and whose spirit was composed of the resentments of countless drowned people. He had to use the method of a beast tamer to "tame" this malicious but powerful ship and its undead crew, sail on the border between life and death, and become the only legendary smuggler and explorer who can freely shuttle between the material sea and the soul reef.
