The International Shakuhachi Society - Biography: Yuize Shin'ichi -, describes his specialty as "koto," and pictures him with what appears to be a 3-string vaguely "banjo-ish" instrument. Based on this, and some additional floundering around the web, I would presume that the instrument shown is a "standard koto."

No joy in finding what a "tashi koto" might be, although a couple of sites say that "tashi" is the name used in a dojo for a karate master of 9th dan who is over 50 years old. That's a big help(?)

The link posted by kat at 20 Jul 03 - 03:11 PM shows pictures of the Bulbul Tarang with "pianoish" keys and "typewriter" keys, and indicates that the typewriter keys are more common, because they're cheaper, but implies that the piano key version is not rare. The different keys thus would not necessarily indicate a Japanese, rather than Indian, instrument. More likely just a Japanese name for the East Indian instrument? - (assuming that the origin of the thing was in India.)

John