I'll be at Tsukuba this Saturday morning for 2 x 30 minute runs. The first is 9am and the second is 11am if you want to go check out what the circuit looks like.

Regarding Fuji and traffic... well, your perspective changes depending on how long you have been here. I've been here 13 years, so I kind of accept traffic these days. There are 3 stages I think,

a) new to Japan - the crowds frustrate you but you still gotta do stuff so you put up with it.
b) used to Japan - you've done most things and know there are times when its not crowded so you only aim to do stuff during those times and other times you just don't do it...
c) given up on Japan - shoganai I think is the attitude here - you want to do something so you just do it. It might be painful but you might be lucky and you'll get through it.

I'm in c sometimes fighting falling back to b sometimes... I figure that Fuji is great so well worth the pain of possible traffic. More often than not, I breeze there and back... Trick is to get to Atsugi before 8am. Some body always crashes around 8am at Atsugi no matter what on the weekend. On the way back, if its crowded, I just go eat something in the parking area and get through it that way :-)

Many tracks around Japan don't have great run off which is a shame. Tsukuba is decent but I've been in the barriers there once before in my RX-8 and escaped them by inches other times. That's why I recommend Fuji :-)

Here's me at Tsukuba just missing the barriers... Yikes.
Roxy - the RX-8: Lucky Number 13!

Not discouraging you at all, I love Tsukuba too. Just not the best place to start out perhaps. Come check out the course this weekend or some other time before you run.

I'll let you know when I go to Fuji next and see if I can get my other CaymanS Japanese friend to come a long also.