Chokai is a great event. A TT on the Saturday and a hillclimb on the Sunday. You can camp for free on the big grass field in front of the onsen. On Saturday night they have music, fireworks etc.
Last time I went was 2006, so really looking forward to it.
13 years later and it's not got any easier!
Unfortunately, we'll be making a flying visit as we fly out to the UK on the Monday. If you have more time though, there is a second route up Chokai from the seaside called the Blue Line, which you can ride up one road and come down on the other. The coast road is also beautiful up there. Gas san too is worth a climb...