The Ijin Three is comprised of three criminal syndicates working together in Isezaki Ijincho to maintain the "Great Wall" that keeps Ijincho underworld under their control and safe from outsider groups such as the Tojo Clan and Omi Alliance. The three criminal organizations that make-up the Ijin Three are the Seiryu Clan, a Japanese yakuza group; the Yokohama Liumang, a Chinese-Japanese triad gang; and the Geomijul, a Korean surveillance and information brokerage syndicate.
Secretly, the organization also operates Japan's largest money counterfeiting operation; a business which only the highest-ranking members of the three organizations are privy to.
During the 1950's, the Yokohama underworld was on the brink of being torn apart by a war between the Japanese Seiryu Clan and the Chinese Yokohama Liumang. However, before war broke out, city councilman Yutaka Ogikubo secretly contacted the then leaders of both groups and proposed a business arrangement between all three of them to prevent further violent escalation: Ogikubo had acquired stolen plates which the Japanese Treasury had used to print 10,000 yen bills and offered to let the Seiryu and the Liumang have access to them in order to counterfeit money together and split the profits. Both leaders agreed and a counterfeiting syndicate was formed, where the Liumang imported the materials necessary for the forgery, the Seiryu produced the bills and Ogikubo used his political connections to keep the operation secret from the authorities.
Through this scheme, Ogikubo and both criminal organizations became incredibly wealthy and peace between the Seiryu and the Liumang was ensured. However, due to the serious legal trouble that could befall them if the counterfeiting operation was exposed; only the top members of both criminal groups could be allowed to know about it, so the Seiryu and the Liumang's leaders distracted their subordinates with the erroneous belief that their organizations were constantly on the brink of war. They also sought to silence anyone who tried to expose the scheme, whether by kidnapping, murder etc.
In 1984, the Korean Organization known as the Geomijul joined the Ijin Three and became responsible for the production of the bills, while the Seiryu Clan remained responsible for distribution of said bills and the administration of bribes to local and nation-wide officials.