Demon slayer Drake finds himself on a bioligist boat after blacking out after destroying Brian. The ship captain Marsh wants him to scuba underwater and explore the unknown seas. But it turns out that king Zunart one of drakes targets is in the unknown seas. But when drake looks at the radar he is suprised to discover that the sea is hollow and Zunart has turned every one on the ship into zombies accecpt Drake. So its up to Drake to defeat Zunart, his crew, and Zunarts demons.