You question sparked my curiosity, and I noticed the same lack of online information that you did.
I'm afraid I don't have first hand experience with the mic so this is purely speculations. I imagine it was made for the Japanese home market, possibly exclusively for NHK (the Japanese national broadcasting company).
The official Sanken company history page mentions that they made the MU-1 as a PA mic for the 1964 Tokyo Olympics in collaboration with NHK. I found only few pictures of the MU-1, but it appears to be a 600Ω dynamic mic.
From the few available pictures of the MU-2, it also seems to be a 600Ω mic, which makes me think it is an upgrade of the MU-1 with similar intended use.
On the most popular auction site in Japan, Yahoo Actions, MU-2s seem to pop up from time to time. All are severely beat-up samples. Most with NHK engravings, some with a funny looking grille/pop filter. They appear to sell at a modest price, around 5000 JPY, which is less than 50 USD.
Given the going rate, I wouldn't expect something spectacular out of the mic.
Topic: Anybody know anything about the Sanken MU-2? (Read 2149 times)