Sung-chul (Park Joong-hoon), a Korean gangster, flees to Japan after killing a subordinate. On the flight, He-gu (Park Sang-min), an aspiring bartender, discovers his true identity and is forced to act as his guide. Despite multiple betrayals and brushes with death, the two form an uneasy bond. As Sung-chul rises through the ranks of the yakuza, He-gu too is drawn into the criminal underworld. Clumsy but determined, He-gu survives power struggles, betrayal, and heartbreak—only to make reckless decisions that ultimately lead to chaos. In the end, Sung-chul is ordered to eliminate He-gu. At the seaside, after one final plea for mercy, He-gu is shot dead by Sung-chul, who walks away silently.

Kingdom of Joseon, ancient Korea. A usurper has conquered the throne. His ministers are being systematically eliminated by a mysterious assassin. An arrogant master swordsman is in charge of putting an end to the carnage.