Japan is a very expensive country to travel. Unlike Europe where travelers can easily move from one country to the next on cheap flights and trains, Japan is a stand alone destination. Most people will book a trip to Japan for a few weeks and then return home.
It’s hard to include Japan on a travel itinerary to Asia without making specific flights for $350 USD in and out. It’s possible to take the ferry to Japan from Korea, but otherwise most travelers arrive at the major international airports. It’s very different from the Southeast Asia backpacking trips.
So I traveled Japan quite differently from the rest of Asia. I volunteered for 4 weeks at a hostel on two occasions and then added a 5th week at the end to go exploring freely on my own. In a way, I lived in the Ancient Capital of Kyoto very briefly, working and making friends. I got to see all the popular tourist sights and then so much more by getting to know my colleagues and other locals. I loved it so much I did it again in Miyajima near Hiroshima.