Pachinko concession is a shared interest between the Japanese police and North Korea. It is a popular gamble legally untouched and you can find those gaming shops all over Japan.
This business used to be dominated by Korean descendant, the majority of which is assumed still to run by them. Some shares of this profit are sent to North Korea, which was one of the main source of foreign fund at least in the past.
The gamble is basically illegal in Japan, but this business is structured to sneak out of its illegality. Having said that, it is a gamble however structured, hence the police might have cracked down if they wanted.
However, they rather took a vantage from their position of supervisor than shut them down that they have established several non-profit organizations to gain a margin from them. At the same time, these organizations hired many ex-police officers to stabilize their retired life.
In this course, North Korea gave a concession to the police department for sharing the interest, which is another side of the relationship between them.
There are several industrial associations under control of the police department, such as Zennichiyuren and Nichiyukyo. Both of them became police associates in 1989, actually not that historical, which also meant their deep relationship started around this time.
There is another important association for their relationship, which is Hotsukyo. This organization was established in 1982 to research a digital information matter by ex-police ranking officers but remodeled to conduct Pachinko interest in 1985.
Pachinko resembles a slot machine, though its winning rate is regulated by the police department to contain the riskiness. This control has been solely managed by Hotsukyo, which is their source of income and this organization has hired many ex-police officers.
This is how they can take a vantage from their policing capability to be monetized as a profit in Japan. Before this organization was built, the Pachinko profit had been proportionally sent to North Korea, which indicated that they gave a concession to the Japanese police as late as in 1985.
This also meant that North Korea took something for this giving up, which was why this deal was done between them. Although, I had still no idea what the police gave to North Korea, which was definitely related to the issue dated before 1985, though it is still above my capacity to clarify what happened to them.