Okajima Rokuro, nicknamed Rock, is a young employee of a Japanese firm: Asahi Industrial. He leads a monotonous life. However, his life as an employee is suddenly turned upside down when he is taken hostage by the crew of the Black Lagoon, who are there to take away the diskette for which he was responsible.
Rock is abandoned by his bosses, and decides to join the crew as a deckhand.
This is how Rock joins Revy, Dutch and Benny.