The Inside

The Inside (中, Naka) is a commonly used term for a massive occupied territory inside of Japan, where Japanese law enforcement has no sway, and therefore laws are meaningless and anything goes.

About
The Inside appears to be located in the southwestern end of Yamanashi Prefecture, covers an area of 47.88 square km and has a population of about 200,000. Formed in and around 1868, the region has no rules and is full to the brim with all kinds of vices including, but not limited to, drugs, violence and prostitution. After effectively abandoning the area in 19XX, the Japanese government refers to it exclusively as the "Illegally Occupied Territories", and puts out propaganda saying that it is filled with a noxious gas where no-one can survive, in order to disguise the truth and avoid mass panic.

It is known for being a harsh kill-or-be-killed environment, full of dilapidated buildings, brothels, and drug dealers, and even the Yakuza shy away from it. The people who are unfortunate enough to live there have to fight on a daily basis just to survive, and often have no education, no papers, and sometimes not even a name. This makes it very hard for people from the Inside to leave and integrate into normal lawful society.