In the treacherous waters of Bilgewater, an accident caused the ship "Surge Will" of old captain Todd Rusty to be eroded by the mysterious "Rusty Tide". Rust tide is a kind of rust bacteria that activates metal. It gives the hull the ability to slowly repair itself, but it also makes the hull extremely heavy and creates a terrible "hunger" for metal. Todd became the slave captain of this "living ship" and was forced to risk his life salvaging metal in the dangerous sea where the rust tide spread, while desperately searching for a way to reverse the rust tide or coexist with it.
Under the shadow of the rust tide, Todd sailed with his crew - including the tough first mate Hal "Ironjaw", the young mechanic Lena "Little Wrench", and later joined the mysterious scholar Selin who possesses ancient knowledge. They encountered ghost fleets swallowed by the Rust Tide, giant sea beasts guarding ancient ruins, and predators eyeing the power of the Rust Tide. Every voyage is a struggle against hungry living ships, unforgiving seas, and inner despair.
