in case you didn't already see this on
GaijinPot... I might try this if I were in the area (and maybe if I understood a little more Japanese). if you do it, you should post about it afterwards; I'd be curious to find out what it was like.
[EDIT: The ad for extras has been taken down, which probably means they've filled all the slots. However, if it's all right I'll leave this post up in case people still want the links.]
there's also a separate page
here for general, all-year-round applications to be on the show [Cool Japan].