During a business trip to Southeast Asia, Japanese office worker Okajima Rokuro was kidnapped by members of the pirate-like transport company BLACK LAGOON. In order to keep secrets, the company sent mercenaries to eliminate Okajima, who became a hostage, but Okajima escaped from this desperate situation with his wisdom. Abandoned by the company, Okajima gave up his name and position, changed his name to Rock and became a member of BLACK LAGOON. The former military boss Dutch, the mechanic Benny, the gunman Revy with the nickname of double guns, and Rock, together, rode the modified torpedo boat BLACK LAGOON on the southern sea. The heroine is the beautiful double gun hero, Revy, who can handle any dangerous job!