Japanese gas stations have self-service and full service.
Full service: It's a little more expensive, but you can leave everything to the staff. In the case of a car, they may help you to throw away garbage and clean your windows.
Self-service: It's a little cheaper than full-service because you do all the refueling and payment yourself. However, please note that the price varies depending on the location of the stand, and prices tend to be higher in places where there are few stands, on the highways or up in the mountains.
The oil types are mainly divided into three colors: high octane: yellow, regular: red, and light oil: green.
Speed: There are various speed limits on general roads in Japan, whether in urban areas or in the suburbs. There are some countries overseas where the speed limit increases as you go to the suburbs, but be aware that there is no such regulation in Japan.
Roads ・ Traffic Jams: Most of the roads are paved. There are roads with heavy traffic. Specially In the city centers. Also, many pedestrians, and the road width becomes narrow. In the city center, traffic jams of tens of kilometers often occur on public holidays and high seasons, so be sure to plan ahead with plenty of time.