OK, when you get to Tokyo, here's where you want to go:
http://www.yamamoto-bass.com/
They're in Shin-Okubo (easily accessible part of Tokyo) and they'll take care of you. Tell me your exact schedule and we'll figure out the logistics. The guy I deal with there is Minoru Kimoto, he's great. I'll send you a pm with my number.
edit-
Hey - is this what you're doing?
http://www.glennmillerorchestra.com/Japan-Schedule.html
if that's the case, and this Monday is an off day in Tokyo, then no problem, take care of it Monday. If Monday's a travel day, that's trickier, but I'm sure something can be done.