Hello Lapa!
I'm from the USA, but I lived in Japan for a little while.
A good thing about Japan is its mass-transportation system. It runs very well and a person can go almost anywhere, quickly, easily, and for a low cost.
So, if you can find a university near Tokyo, Kyoto or Osaka areas (which have the most Vegan restaurants and food stores), then you can use the metro-train-bus-taxi system to visit these places.
A strategy for learning and working in Japan:
You may wish to consider going to Japan to work as a Language Teacher.
There are many non-Japanese people* who teach their native languages to Japanese people. The pay is very reasonable, plus you can develop contacts with other people for work, study, etc.
English is very popular among Japanese people, but Japanese people are interested in other languages too.
Perhaps you could teach English as well as your native language. By doing this you can study Japanese language and culture and then enter into a university with great experience (?).
The best places for finding this work are Tokyo, Kyoto, Osaka, and other larger cities. It is not very difficult to find this kind of work and once you have experience teaching you may find work with no difficulties.
*Many of these people are young (student age) and mostly live in the Tokyo area and also Kyoto and Osaka (and some in smaller metro areas). For some more ideas, visit YouTube.com (on the www) and search for Japan, Tokyo, English teachers, etc. and you can view many video reports by non-Japanese people who live, work, and study in Japan.
Gambatte Yo! (Go For It!)
Good luck (stay Vegan no matter what ...)