He is voiced by Daisuke Namikawa in the Japanese version of the anime and Brad Swaile in the English version, the latter of whom also voices Light Yagami.
Rock was born into a well-to-do but neglectful family in Tokyo. He entered college one year late and his family lowered their expectations of him, whereas his academically capable older brother landed a job with the Japanese government. Rock lived an unremarkable, demeaning existence as a white collar salaryman for Asahi Industries at the start of the series.
During a business trip in the South China Sea, Rock's ship was hijacked by pirates from the Lagoon Trading Companywho sought a data disk he carried; he was taken hostage byRevy and her fellow pirates, Dutch and Benny, and kept aboard their PT boat, the Black Lagoon. Instead of helping Rock or negotiating a ransom, Rock's department chiefKageyama abandoned him in an attempt to cover up the smuggling operation in which he had been involved. Kageyama sent out a group of mercenaries to kill Rock and the Lagoon Company and destroy the disk.
However, Rock—even though he never experienced combat—helped the Lagoon Company defeat the mercenaries by using the Black Lagoon's anti-ship torpedoes to shoot down the mercenaries' attack helicopter. Rock is left invigorated by the experience of piracy. Unwilling to return to his former life in Japan, and having been told that Kageyama has already declared him legally dead, Rock decides to stay in crime-infested Thai city of Roanapur and joins the crew of the Black Lagoon.