I also have one other suggestion in case you’re more interested in history and Old Japan.
Instead of flying into Tokyo, fly directly into Osaka and focus your trip around the ancient capital Kyoto.
Kyoto was the capital of Japan for over one thousand years (before moving to Tokyo), and today it’s a fascinating city full of ancient temples, shrines, gardens and living traditions.
You could spend weeks in Kyoto and never see it all, but three or four days here will give you a great taste of the city – and you’ll have to come back again another time!
To complement Kyoto, spend your last day or two in nearby Osaka for a taste of modern Japan.
Osaka is a huge, lively city, with famously-outgoing people and an exciting dining and drinking culture.