Had to go to Japan last week for work and had Friday free, so me and a colleague decided to rent a car (an adventure in and of itself) and drive to the Twin Ring Motegi track. It was awesome. There appeared to be some sort of open track day with sessions alternating between some serious DE-type cars and some form of small formula cars. We essentially had the place to ourselves, though and evidently you can go whevever you want (garages, paddock, pit road...).
The real reason we went, though, was the Honda Collection Hall. It's a museum of everything Honda. We were the only ones there for most of the visit. Easily the best automotive museum I have ever visited. I had chills most of the time walking from one piece of history to another.
Some pics:
If you ever find yourself in central Japan with a day to kill, I highly recommend this place. The museum is free with entrance to the track (which was only 1000 Yen - $10). We rode racing carts, ate the best track food I've ever had, shopped in amazing souvenir stores, etc. Great place.