No matter where you go or what time period you're from, crime is always present. Whether it be organized crime, petty street gangs, or a lone thief, as long as laws exists there will be people willing to break them for survival or a greater purpose. Fact is, people will always be willing to pay for jobs that are unsavory that they otherwise cannot carry out themselves for whatever reason.
Although criminals exist everywhere in the world there are certain places where they thrive. These "Underworld Districts" are commonly associated with ghettos in larger settlements. They only exist in large enough settlements (at least Village-sized dwellings) and grow as the dwelling does. A village-sized dwelling will naturally accumulate a Crime Rating of Level One over three months upon creation. This is a byproduct and consequence of having a large population. By developing a criminal rating your dwelling will automatically create an "underworld", a system of crime which happens beneath the public eye. These will essentially serve as an Administration and a Market for people who are rogue and otherwise cannot report to a Kage for missions or buy from the typical market.
Although criminals exist everywhere in the world there are certain places where they thrive. These "Underworld Districts" are commonly associated with ghettos in larger settlements. They only exist in large enough settlements (at least Village-sized dwellings) and grow as the dwelling does. A village-sized dwelling will naturally accumulate a Crime Rating of Level One over three months upon creation. This is a byproduct and consequence of having a large population. By developing a criminal rating your dwelling will automatically create an "underworld", a system of crime which happens beneath the public eye. These will essentially serve as an Administration and a Market for people who are rogue and otherwise cannot report to a Kage for missions or buy from the typical market.