Before Takemitsu started to compose Eclipse, he was reticent to use Japanese traditional instruments, because, as he puts it, their sound "always recalled the bitter memories of war".
Since this first collaboration, Takemitsu started using these instruments more often, as seen in Shinoda's Assassination and Masaki Kobayashi's Kwaidan.
He finally composed Eclipse in 1966 and premiered it that same year with Kinshi Tsuruta at the biwa and Katsuya Yokoyama at the shakuhachi.
[4] In the score of this composition, the notation system is slightly different and has special symbols to cover the different possibilities of the two instruments, for they are normally used only in traditional musical context and had been rarely used in concert pieces before.
The score of the biwa consists of a special tablature system which is enhanced with pitch alterations, attack qualities and the like, whereas the shakuhachi player has to read lines and shapes on a time axis.