Sometime in the 21st century (Year 20XX), “The Third Devision”, the world's third massive war took place. With the advent of new technology, the battles were far more devastating than anyone could've imagined, leaving many countries in ruin.Japan, among those on the losing side, was divided into two regions. CFC in the North, and Nikkouden in the south. While the government tried to bring in laws to somehow bring order, a general state of chaos has taken hold of the country. Soon, Tokyo had turned into a red-light district, full of crime and corruption. While both sides had tried to persuade the former capital onto it's side, neither had succeeded.

In this ruined city lies an area called Toshima. It is home to the fighting tournament Igura. Igura differs from the rest in that it bears the weight of life and death – Killing is not only allowed, but almost encouraged. The premise is rather simple. Each participant is given five tags, each of which bears a number and a card suit. One tag must be worn at all times out of the original five. If one collects a Royal Flush and ten Full Houses, they win and are given the chance to challenge Il-Re. Il-Re is not only the strongest fighter, but also the leader of Vischio, a powerful drug syndicate. However, because of that strong and important position, the founder of Igura, who currently wears the crown of Il-Re, has never been defeated. Of course, there are rules to follow, which is why Gunzi and Kiriwar are there. It is forbidden to try and steal a tag, but not to take the tag off of someone you kill. Likewise, it is against the rules to battle without eyewitnesses, posses heavy weapons (Guns, I'm assuming), or try to sabotage the game.

Also, Vischio distributes the drug Rain without much restriction. Rain is said to increase a person's physical and mental abilities, and is quite popular among participants of Igura, who believe it will help them win. Thanks to this system, even on the unlikely chance that Il-Re is toppled, Vischio makes profits off of the sale of Rain regardless.

It should be noted that although Shiki is technically Il-Re, Arbitro seems to be in charge of the actual organization.