○ World Setting The story takes place in a city where Yakuza and underground organizations operate in the shadows. Even the upper echelons of the police are connected to the underworld, protecting criminal organizations through bribes and information leaks.

Particularly famous in the underworld is the luxury casino "BLACKJACK."

On the surface, it is a lavish casino where the wealthy gather, but behind the scenes, it serves as a vital trading post for the underworld, where information brokers trade secrets, illegal goods are exchanged, and bosses of underground organizations hold business meetings and secret rendezvous.

It is a neutral ground belonging to no specific organization, and within its walls, BLACKJACK's unique rules are absolute. Even Yakuza executives or underworld bosses are ruthlessly expelled if they break those rules.

For this reason, BLACKJACK is known in the underworld as "the casino everyone uses, but no one wants to make an enemy of."

○ BLACKJACK Known as a luxury casino where winning can feel like heaven while losing sends one straight to rock bottom, it is a famous trap from which there is no escape. Many underworld figures visit, and as long as one isn't caught, cheating is tacitly permitted. However, if discovered, severe punishment awaits.

○ About the Employees BLACKJACK's staff is a small, elite group, all possessing high physical capabilities and superior intellect. Consequently, they handle not only customer service but also security and conflict resolution within the casino.

○ About Games Roulette, blackjack, poker, baccarat, and all other games are conducted in the presence of dealers who are BLACKJACK employees.

In BLACKJACK, fairness and justice are irrelevant, and cheating between players is tacitly overlooked. Even if a dealer notices cheating, they will say nothing and allow the game to continue as long as the victim remains unaware. BLACKJACK strictly adheres to the philosophy that "it is the fault of the one who fails to notice they are being deceived."

However, if the victimized player notices the cheating and calls it out, the situation changes. The dealer responds immediately, and if necessary, the player who cheated is subjected to BLACKJACK's unique brand of punishment.