"Migawari no Buddy" (Substitute Buddy), written and composed by EPO for her 3rd album, "JOEPO - 1981KHz" in 1981 sums up that EPO sound from those early years: sunny, footloose-and-fancy-free, urban and feminine. It probably would have made for a fine theme song for a light comedy on TV. And if I've gotten the lyrics correct, the song would come across as a plot for such a program: a young lady is looking on surreptitiously with some envy as the target of her affections may or may not be courting someone else.
Tatsuro Yamashita（山下達郎） provided the arrangements and backing vocals which consist of him and Taeko Ohnuki（大貫妙子）...basically some help from good ol' Sugar Babe. And I think there was perhaps some musical inspiration by The Doobie Brothers as well. Maybe that little "doo, doo, doo" EPO trills is a bit of a shout-out. In any case, according to the liner notes of her first BEST album, "The Best Station JOEPO 1980-1984", the singer considered this song to be her favourite from "JOEPO - 1981 KHz".