Japan is such a great country for travel because its really easy to access.
The thin shape of Japan allows one to cross from top to bottom quite easy.
Trains are the prefered method of transportation, especially the Shinkansen which is high speed.
Japan is a country that you should 100% visit. Not only visit but its a great place to live. The history and culture is amazing. You will never know what you are missing till you take the time to travel across the country, not just stay in Tokyo where 30 million people live.