Itou Kaiji is a bum who steals car emblems and slashes tires on what seems to be a regular basis. This routine changes one day when he is paid a visit by a man in a trench-coat. Once the two get talking, it seems that the visitor (Calling himself Endou) is a debt collector. The reason for his visit is an unpaid loan which kaiji had previously co-signed for a work-mate (Furuhata Takeshi). The original loan was 30000 yen and once Takeshi had disappeared, the loan then fell on Kaiji.
Kaiji is then told of a way to clear the interest compounded debt (which stood at 3,850,000 yen), which involved getting on a boat with others in his position. Once on the boat the debtors would then have to gamble with loaned money, which would end with a few winning, and others getting into deeper debt and having to work to pay of their debts. After some coercing kaiji accepts a position on the boat, in order to clear himself and make a bit of money as well...
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.
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.