In 1965, with the post-WWII era fading into memory, the police tighten their grip on the remnants of the crime networks that once ruled the streets. Amid this shifting landscape, 30-year-old Kensaku Gunji [Bunta Sugawara] steps in as the 4th head of the Hamayasu family, taking over the position left vacant by the imprisoned Tetsuji Kuroki [Koji Tsuruta]. Gunji operates from a cramped corner of the Port of Yokohama, where the old rules still hold sway and where loyalty is tested at every turn.
When Onuma, a Hamayasu member, is arrested under the Port Labor Act, shipping grind to a halt and the entire operation trembles. Onuma’s wife pleads for help, but the crimes of the past haunt him, and another arrest seems likely. Iwakiri, a rival gang boss, eyes a larger prize: a chunk of warehousing rights tied to a colossal new factory complex built by Oriental Heavy Industries. To seize this opportunity, Gunji must clear out the slums that cling to the land where the factory will rise. He refuses to abandon the place where he grew up, but is warned that if he doesn’t move, the Daimon organization from Tokyo will do it for him. The choice is forced: Gunji agrees, yet asks Kasama Tsutomu [Kysuke Machida] to resign so that Kasama won’t have to evict the elderly who still live there. Kasama refuses, vowing to take charge of the eviction himself.
Gunji’s attempt to speak with the slum residents erupts into hostility as the people heft stones and even a dead cat toward the Hamayasu emissaries. Kasama’s father rails against his son’s involvement in the yakuza, while his mother laments that she should have killed him at birth. A brawl spills into the street, but the violence is interrupted by Hayami [Hideo Murota], an old friend who once fled the slums to become a boxer. He returns on a small boat christened the SS Black Dragon and takes a stand to protect the people who raised him. He meets Joe [Ken Sanders], a gifted but battered rookie whose eye injury from a recent bout has left him unable to afford the surgery that could save his sight. Hayami denies Joe an easy return to hustling, promising instead to secure the operation Joe needs so he can chase the dreams Hayami once chased and lost.
The next day, the Hamayasu and Iwakiri gangs descend to destroy the livestock in the slum and torment its residents. With no safe path to the police due to their illegal squat, the people barricade themselves inside their shanties, gaining defensive strength but cutting themselves off from income. Three miners from Kyushu attempt to pass as slum dwellers to claim the compensation Daimon Construction has offered for leaving the land.
Tetsuji Kuroki is released from prison and returns to the Hamayasu, visiting a former lover who now works as a bar waitress. She confesses she has waited years, but he resists letting her become tangled in his dangerous world again.
Hayami accepts money from Daimon, allowing his men to enter the slum and pressure a family into selling by force. The next morning Daimon soldiers arrive, and Kasama, Ozaki, and other Hamayasu fighters are beaten after resisting; the slum’s sale is forced by the deed. Gunji receives a letter with Kasama’s severed pinky as an apology, signaling Kasama’s intent to act alone. Kasama invades Daimon Construction’s office to kill their boss, but is captured and chooses suicide by biting his own tongue. The stern Daimon enforcer Katagiri tells Gunji to come alone to collect Kasama, but Gunji reveals Kasama’s letter and pinky to prove that Kasama acted independently. Daimon demands a 50% share of the warehousing rights in exchange for quiet, and Kuroki arrives, fighting off the Daimon crew and warning that there will be blood if they persist. Kuroki ultimately kills Iwakiri, then collapses after a final, brutal confrontation; the Daimon gang finishes his allies as well.
Daimon Construction moves in heavy machinery to flatten the slum, while the waitress helps pay Gunji’s bail. Gunji and Hayami visit Kuroki’s grave, and then together they survey the wrecked slum and the remnants of the SS Black Dragon. Realizing they have been puppets in a larger scheme, they unite to disrupt the groundbreaking ceremony for the new factory complex. In a climactic clash, they stab Daimon to death but are themselves slain by other Daimon gang members. With the factory’s completion the following year, Japan’s GDP climbs to become the second-largest in the world, trailing only the United States, a stark reminder of the brutal costs paid by those caught in the gears of progress.
