Bathrooms
Most Japanese people take a bath, not only take a shower. Many Japanese baths have re-heating system. There are also public baths. They also have filter for showerhead, not only for faucet in the kitchen for drinking water.
Laundry
Many Japanese do their laundry every morning. Instead of using a dryer, many hang their clothes to dry outside
Telephone
In Japan, local calls are NOT free. Toll free numbers start with 0120-…, instead of 1-800. Phone cards are not rechargeable and users insert the card in the public phone, instead of punching in their card number. (they obviously can’t use it from home)
Unlike in the U.S., they have to pay more when they call a place that is farther away.
Restaurant
In a restaurant, waiters/waitresses usually serve wet towels before starting a meal. they do not have a custom to leave tips on the table.
Gas
Majority of gas stations only provide full-service, instead of self-service (but of course, you don’t have to pay tip!) Gas is very expensive in Japan comparing one in the U.S. 1 Gallon of gas can cost $ 3.50 in Japan
Traffic
In Japan, they don’t say green light, but they say blue light. Most traffic lights for automobiles are horizontal, instead of vertical, like in the U.S. The speed limit of normal roads is 60kmph (about 40 MPH) and highway is 80kmph (about 50 MPH)
School
Smarter students are encouraged to help out slower students. They don't have honors classes, so you won't find as outstandingly genius kids in Japan as you do in the US, but on average, you won't find as many stupid kids and drop outs like you do in the US. Most elementary and middle schools have their own pool. Students clean their classrooms and hallways by themselves. A new academic year starts in the spring, April, instead of Fall. Students wear special indoor shoes once they arrive at school.
Guns
In Japan, they are NOT allowed to possess guns and swords. they can’t even bring a knife over 2 inches without proper reasoning.
Alchohol/Drugs
Drinking age is 20 and isn't very taken seriuosly. However, weed and other drugs are a big taboo.
Hmmm...
Teenage girls' used underwears are sold in vending machines.