“Upskirting” is the term given to the act of someone taking a photograph up a girl’s skirt. This is unfortunately a very big problem in Japan, although it does not happen to foreigners any more than locals. In addition, women are sometimes groped on trains, especially during busy times. Many measures have been taken to tackle this problem including having ‘Women Only’ carriages on trains, but it still happens in crowded areas.
Beware of pickpockets as they tend to operate in tourist areas, keep your belongings secure at all times and be careful if strangers try to make conversation or distract you as it could be an attempt to steal your valuables.
Credit card fraud, cloning cards can be an issue be careful where you use your cards. Also if you are withdrawing money from cash machines make sure you cover your pin and be discreet about the amount of cash you withdraw.
The city centre like Shinjuku, Shibuya and Roppongi are probably the most dangerous as a lot of people drink there and there are more clubs there, so take extra care.