Is it your first trip to Japan?
What are interesting things for you?
If you are interested in traditional Japanese culture,I recommed visiting
Kyoto city where traditional Japanese cultures are filled.
Kyoto Travel Plans | kyoto-okoshiyasu.com
Shinkansen (bullet train) brings you Kyoto from Tokyo station in only about 3 hours.
And you can see Mt.Fuji from the window while you are Shinkansen.