Months after the events at the Starside Hotel, Kaiji runs into loan shark Endoh in a chance encounter. Kaiji is forced into labor in the Teiai Group's underground mines to pay his enormous debts. Workers are paid a slave's wage in scrip called Perica, making what amounts to ¥350 a day. Those who save up enough Perica are allowed a one-day furlough above ground. Kaiji resolves to do so, but is soon tempted by the foreman Otsuki.

Kaiji agrees to play Chinchirorin with the other workers and foreman Otsuki. Kaiji spends several rounds making small wagers to get a feel for the game. Dissatisfied with the small payout, Kaiji bets big- 3,000 Perica against the timid man Miyoshi.

Kaiji loses his first bet of 3,000 Perica, but strengthens his resolve to fight. He continues to make bets of 3,000 Perica. After 40 minutes of gambling, he ups the ante and bets 5,000 Perica against foreman Otsuki and his lackey. They respond with enormous bets- each betting the house limit of 20,000 Perica.

Weeks have passed since Kaiji's crushing loss on gambling night, and he finds himself in a cycle of debt with a group of five others, including Miyoshi. The group is referred to by the other workers as the "45s". With the help of Miyoshi, Kaiji discovers that the foreman's group is cheating. Kaiji rallies the 45s together to come up with a plan.

While Kaiji is on medical duty, he meets the son of Ishida, Hiromitsu, who is also working underground for his debt, but blames his father for not bailing him out. Angrily Kaiji berates him for not accepting his own weaknesses. Later, Kaiji insults Ōtsuki who then makes life a misery for Kaiji and the Forty-fivers, but after three months they all return to full pay. Meanwhile, Kurosaki Yoshihiro, Tonegawa's replacement, observes Kaiji through CCTV. When the gambling night begins, Kaiji proposes no betting limit before he will join in and Ōtsuki accepts.

Kaiji and Ōtsuki prepare to face each other over cee-lo, each thinking they have an edge. For the first few matches, Kaiji does not bet over the old limit of 20,000 perica and everyone gets bored with Kaiji betting so little. On a challenge from Ōtsuki who must deal twice, Kaiji bets his entire 52,000 perica and signals the Forty-fivers who each bet 92,000 perica, for a total of 507,000 perica.

When the foreman sees that the Forty-fivers have bet all their money, he suspects that Kaiji has discovered how he is cheating. A backstory is then shown of when Ōtsuki and his men started cheating after purchasing special dice without the 1, 2 or 3 dots. Back at the game, Ōtsuki is forced to play with normal dice, taking his chances, but then suspects that Kaiji does not know how he cheats, so on the final throw he uses his special dice. Suddenly, Kaiji grabs the dice before they stop rolling.

Kaiji shows everyone that Ōtsuki is cheating by using his special dice. He then tricks the foreman into betting again while Kaiji and his group use their own "special dice", with a 1 on each side, and thus Ōtsuki is forced to pay 5 times the amount they bet, losing 2,535,000 perica in total. Just when Ōtsuki was about to give up for the night, Kaiji reminds him that he still has to deal one more time according to the rules. The Forty-fivers then bet all 3,042,000 perica against the dealer.

Kurosaki intervenes and tells Ōtsuki that he has no choice but to play, and in the end, he loses 18,252,000 perica which Kaiji splits equally between the Forty-fivers. Kaiji then asks Kurosaki to approve their requests for the one-day outside pass and he agrees. The Forty-fivers insist that Kaiji should keep the money and twenty one-day outside passes, leaving him with ¥800,000 (around US$7,800) to gamble for the team and pay off their debts. Now back in society above ground, Kaiji meets Sakazaki Kōtarō who is looking for a partner to win big in the illegal casinos. Kaiji accepts his offer, and is taken to an illegal casino where he sees a huge Pachinko machine called "The Bog". Each ball is worth 1,000 times more than normal and the jackpot is worth ¥550 million, more than enough to free Kaiji from debt.

From his descent into the underground hell to his first encounter with the Bog and Ichijou, relive Kaiji's journey and see just how far he has left to go.