Although security in Japan has been getting worse recently, I think that Japan is still relatively safe. There's a good example to prove it. When my Chinese friend who just moved to Japan a few months ago went to an electric retail store, she put her purse somewhere and left the store. A few hours later, she realized that she had forgotten it. She immediately went back to the store and asked a shop staff whether or not the store had her purse. Against her expectation that it would not have been found, the store had her purse. Despite being valuable things in her purse, she got it back without anything being stolen. This incident actually astonished her.
I'm proud of the safety in Japan, and hope that the safety will continue to be preserved. However, I'm sometimes surprised by Japanese people's careless behavior toward their personal belongings. This may be because my experiences when living abroad have made me accustomed to always keeping my eyes on my personal belongings whenever I go out.
When I went to a self-service cafe with my Slovak friend in Tokyo, some behavior of Japanese women stunned her. To reserve seats for themselves, they first left their personal belongings on the table and the chair, and then went to a counter to buy a cup of coffee. Some of them even left their cell-phones on the table. They seemed to be fully confident that their personal belongings left on the table wouldn't be stolen, even though it was impossible for them to keep their personal belongings in sight. It actually took them some time to return to their reserved seats because of a long line in front of the counter. My friend was surprised and asked me whether or not anybody would intend to steal their personal belongings.
I think that behavior is not acceptable any more even in Japan.