Top 5 fundamental Japan travel tips are:
1. Time Difference
Japan time zone as if set to GMT it is +9 hours. So it is 1 hour faster than most of the Asia countries.
2. Language
Japanese is still the main language that widely use in Japan public, private and government body. A lot of younger generation people do speak English but they are speaking in Japanese mixing English term with very strong Japanese pronunciation flavor, so it is very strange or sounds funny when you first time hearing this. No worries, helpers or workers in tourist spots, hotels and restaurant are all well trained with English speaking skill and fluency. If worst come to worst, you still can use your pen and paper to draw some pictures or direction on map that wish to go.
3. Power Source & Plug
Japan is using 100 volt, with two straight thin flat pin, it is different from some of the Asia country and different to Europe countries too. Digital appliances should be supporting 100 volt - 240 volt, just to make sure, you need to counter check your digital travel gear. Also you need to equip with universal power plug just in case.