Floo: here is some article about Koto.

KOTO is a kind of zither. It has been used as one of the main chamber instruments of Japanese traditional music style.
The length of KOTO is about 180cm. A traditional KOTO has 13 strings, being arched tautly across 13 movable bridges along the length of the instrument (right picture). Players make base pitches by moving these13 bridges before playing.

History of KOTO
From 7th to 8th century, cultural embassies were sent to China to learn and aquire its political and cultual system. They also borrowed some music instruments, among which was cheng (KOTO). At first, it was used in court life and later it was played mainly by blind musicians (almost all Japanese pre-modern music were played by blind musicians or monks and court people).
In 17th centry (Edo era), YATSUHASHI-KENGYO (1614-1685), one of the blind KOTO masters, succeeded in moving KOTO to solo-instrument. Thus he has been known as the father of modern KOTO music. He made many compositions for KOTO music, and many of them are played now.

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