This is an interesting one. It came out in 1994. Apparently only 3 of them were ever sold. One to a Music Store in Cologne, another one to a sonic research center in Isogawa, Japan and a third one to a Robot research center in Nara, Japan. Price: about 30000€.
It never got properly released by Yamaha.
It's a 16 note polyphonic virtual acoustic synth with free running VA oscillators. It's design is in the same fashion as the Yamaha VL-1 and the VL-7.
Here's a good source for more info and sounds.
The Owner's manual can be downloaded here.
The Perfomance Notes are here.
I want one! Only a pity that it's as rare as hens' teeth and that it would cost a fortune...