There will always be those types of people out there who take what's rightfully not theirs to keep or to sell for profit. No matter where you are in this world there is no place safe whether you're in Nigeria or Japan. Just as most people (such as myself) would claim that Japan is one of those countries where you could leave your gear laying around and it'll still be there, you should think again.
Unfortunately I learned the hard way by not having my gear insured or having at least some type of protection measure to fall back on when some of my equipment was stolen from me. If you don't have proper insurance for your photography gear then the very least that I can recommend you do is head over to www.lenstag.com and register your gear with them.
It's better to be somewhat safe than sorry.