Today, I met a guy who went to TUJ in 2006, and he mentioned this to me as something he did while he was there. It sounded like a lot of fun, so I looked it up.
http://www.japanprobe.com/?p=3014
Sounds pretty wild actually... and I don't know if I'd wanna risk it. From the looks of last year, it may get ugly this year. I'd only wanna go just to ride around a train in costume and take pictures, nothing else. But we'll see.....
