Set in the heart of the corrupt city of Roanapur within Thailand, Black Lagoon follows the story of Rokurou Okajima, a mundane Japanese businessman seeking a break from his routine life. His mundane existence takes a sharp turn when a delivery trip to Southeast Asia lands him in the clutches of the notorious mercenary group, Black Lagoon. Left abandoned by his employer, Rokurou opts to join this dangerous outfit to survive the treacherous underworld of crime and violence. As he grapples with his newfound reality, Rokurou faces a moral dilemma, transitioning from a white-collar worker to a gritty mercenary, all against the backdrop of a thrilling and morally complex narrative.