"Yoko"（杳子）is a name of the Japanese cinema in 1977.(I have never watched it.)It was made by young stuff and private production.It seems an experimental cinema when I read the plot.They decided to use synthesizer music in the cinema from the start ,just like "MORE"(Pink Floyd) and German electronics..
Then Toru Hatano (畑野亨）was asked to make the music.At that time ,he was 23 years old ,and he made the OST without watching the cinema for one year (from 1976 to 1977).
Hatano was a drummer of legendary group ESCAPE (Masayoshi Takanaka went to FLIED EGG), the ESCAPE appears on the album titled "BRUSH!?"(1971) .