Itou Kaiji is a loser without a steady workplace or money. One day he is told that his friend, who had a debt of two million yen, is gone missing, and Kaiji is the guarantor of this huge debt. Kaiji can't afford to pay off the debt, so he is given a chance to go on the gambling ship Espoir -- French for 'hope' -- to clear the debt in one night. But it isn't as easy as it seems: it's a game of life or death.
Both are about games people play so that they can get rid of their debts. If they win, they can do it. If not, they will fall into even more debt. While playing, the guys who set up the game and the players who want to win no matter what try to lie and deceive the main hero/heroes, who have to save their own life, and believe in justice.