Kaiji Ito is a total loser. He didn't have a regular job, and was just loafing around in Tokyo for three years after graduation from high school. He lives day by day gambling, making small debt and taking out his frustration on expensive imported cars.

His life changes one day with a visit from a loan shark, Endo. Endo was going after Kaiji's ex-coworker Furuhata's debt, to which Kaiji was a cosigner, but the outrageous interest rate boosted Furuhata's debt up to the amount Kaiji could never cover.
Endo then seduces disheartened Kaiji. "You can wipe the debt away in one night." One month from Endo's visit at midnight, Kaiji is on a luxury liner "Espoir", This ship named "hope" is loaded with young losers on the edge like Kaiji, who all plan to win to get off this gambling cruise ship without debt and even making extra money. The ship is actually a harsh and risky battleground of life-and-death game. Can Kaiji win and survive the battle to get off the ship?