Is there any district known for crime in Japan?

Question:

Well, I'm making a manga and I want to setting to be under these reccomendations:

-preferably in a popular prefecture like Kanto
-has to be known for crime (or place in Japan where most crime takes place)
-preferably an also busy place (not as busy as Tokyo)

That's it. Thanks!

Answer:

Kabukicho is not that bad. I walk through Kabukicho at midnight, it's a more colorful place then it is dangerous.

Also it depends on what you mean by "crime". Kabukicho in Tokyo is far from being "dangerous" for people. Not all crimes = dangerous. A lot of illegal activity might happen though.

If we were to use that as an example, I would say Osaka because of the high concentration of Yakuza (Japanese mafia) headquarters found in Osaka.

Remember it depends on what are you looking for:
CRIME does not always equal "dangerous".