Security in Japan is pretty good.
However, there are some places where security is not good.
The author, who has lived in Japan for 30 years, will explain the security around Tokyo.
The following three points are not particularly good. (It’s just an individual opinion)
Kabukicho (north side of Shinjuku)
Southern Kawasaki (around Haneda Airport)
It seems that there are many pickpockets in the southern part of Kawasaki. There is no murder.
In Kabukicho, there are bars that charge a large amount of money.
Stop following the guide standing outside in Kabukicho.
I don’t hear good rumors in Adachi Ward. It seems that there are many weirdos.
That was the security around Tokyo.
It’s basically safe in Japan as a whole, so don’t worry, you don’t have to be too careful except in the areas mentioned above!