The size of the collection of the museum is estimated at about 6 million pieces. The museum recently (1996-7) achieved National museum status as the first National University Museum; it also became a fully functional, exhibiting museum, rather than just a storage/research facility. There is also discussion of using the museum for extended training of curatorial museum staff from around the country.
If your browser can handle frames and Japanese fonts, please have a look at their website http://www.um.u-tokyo.ac.jp - here are some video-captures I made during the museum's exhibition "The Digital Museum" in April, 1997.