Just like any other major city in the world - in the morning and early evening when everyone is trying to maintain or operate. Did you know that the majority of the population of Tokyo is more than an hour every morning, moved to go to work? This is the reason every subway station has its own Gingles - canned sleep if someone ...
If you accidentally the wrong train, there is no reason to panic - there are no "raw" areas in Tokyo. That means - you always need some kind of common sense practice. The red light district of Shinjuku at night was reported to be problematic. But apart, one can confidently explore every corner of Tokyo.
There are no particular health problems in Japan. There are no vaccinations or medications are needed. Japan is one of the cleanest countries in the world, so you can enjoy a meal anywhere in Tokyo. Taps is safe to drink.
