The japanese Kokyu is a bowed string instrument closely related to the shamisen. Wikipedia has a good basic background on the instrument. It's also closely related to the Chinese Erhu.
There seems be be very little in english about this instrument, so this will be my attempt to add to the resources out there. The biggest problem is I don't speak Japanese, I have no teacher and most of what I'll be doing with this instrument is my best guess, so please, take the information here with that grain of salt.
If you have any corrections or information or even just people I should talk to, please contact me at cat at mit dot edu.