OK now that we know there are a few of us going, im trying to find things to do to fill the time there.
Here are a few suggestion:
Nismo Festival
Half day in Odaiba, check out Palette Town, ferris wheel etc
Chiba for Crystal and Top Secret
Hire a van for night out at Diakoku Futo. Drive the C1 loop?
Any Sumo things happening?
Any track days at Tsukuba, Honjo or Mobara?
When is the REV SPEED Time Attack on??