You should always have your passport with you when going out. In Japan, it is not uncommon for the police to ask a local or a foreigner for identification anytime, anywhere.
People Also Ask
The hotel business law requires only foreign nationals who live outside of Japan to present ID. But hotel receptionists sometimes ask foreign people who live in Japan for ID based on their name or appearance.
You can dress as casually as you like in Japan . Just a warning though , Japanese women (even the casual ones) are 1000 % more formal than I am on a casual day. The thing you'll notice is you will rarely see a person who is not well-kept. The clothing is almost never old and personal presentation is much more..
Japan, for example, cannot do background checks on US citizens as they are barred by law from doing so. Unless you volunteer information, they won't know. Why does the US have so many criminals? Because they put the bar so low.
Smoking and buying tobacco is illegal in Japan under the age of 20. Just like when buying alcohol, shops may ask for an identification to verify your age. Although cigarette can be purchased 24/7 at a variety of locations including vending machines, unfortunately, tourists can not purchase it from there.
Casual clothing is common in Japan outside of Tokyo's business district. Shorts, jeans, and camisoles are perfectly fine to wear as long as you don't plan on attending religious sites.