I can't recall the exact date but I had a copy of Sakura with six variations back in the 1970s. It was part of a collection (no longer available) published by Gendai Guitar containing two or three Japanese songs and some arrangements of old classics like "Autumn Leaves."
The version commonly performed today is different - only four variations. This appeared around 2000 (I think) and was picked up by GSP.
You can buy the collected works (below) from Gendai who may have the details that you're looking for.
They spell his name Yuquijiro Yocoh by the way:
Sakura Variations (second version)
Variaciones sobre un Tema de N. Paganini
Cinco variaciones sobre un tema !Feliz Ano Nuevo!
Introduccion, Tema y tres variaciones sobre un aire ingles
Cancion de Cuna sobre una melodia de Matvei Blantel
Cancion antigua Irlandesa
Leccion de Ligado
Fantasia sobre Mikuma-River
Sueno sombra de un arbol
Regalo del Ano Nuevo
Romanza sin palabras
Guardando la casa
Cancion de abuela
[Duo] Sonatine - dedicado a mi mama