12C: Medieval Period
The birth of new genre of Koto from temple music
In kamakura-era, when the power of nobles declined and samurai or monks began to distinguish, Koto was spread as an instrument of temple music. In Muromachi-era which Japanese style pictures, gardens, architectures, and cultures become prosperous, people started to pursue many ways of playing and types of Koto. In the end of this era, the monk named Kenjun from Fukuoka composed several songs based on Gagaku.
And then, the new genre named Tsukushi-Ryuso-Kyoku was born. When the Warring States period started in Japan, many successors carried on the same way as Kenjun.