Going to be in Japan for about 1-2 months

[epik1]

Hey guys,
I'm gonna be visiting Japan in about a month's time and I'm trying to plan it out, I'm going to try and get my IDP (international drivers permit) before I get over there.
I'll be staying in the Gunma prefecture.

Obviously I'm interested in hitting up all the tracks! (Nikko, Tsukuba, Suzuka, Ebisu, Maze, maybe Bihoku, but it seems like it's the furthest from Tokyo)
Do all the car things, visit the shops (Tec-arts, Spoon, Garage Mak, Daikoku PA).

And I'm even looking into Fun2drive, Powervehicles, "All That Low" for fun car rentals.

Other than getting my JR pass, can anyone give me tips or recommendations ?

Thanks!