I'm in Japan, so I've looked at the logistic to go to Tanegashima Space Center. From Tokyo, it's like a big plane to Kagoshima, then a small plane to the island, and then a bus (if you're lucky) or an expensive taxi I guess. Of course, you could also take a ferry with a car from Kagoshima.
The problem isn't transportation, it's the fact that the best (and arguably only "worth the effort") viewing spot is a park whose access is restricted to only a few hundred people during launch… and as usual for limited things in Japan, it's a lottery system. :(