[ayumisrael]

It depends though since there are way older releases than the 80s that sold millions, like the best selling single in Japan was released on 1975 and it sold around 4,536,000 copies.
I know that popularity doesn't always are equal to sales but you would think that the popular most iconic ones would have at least some impressive numbers for certain releases. I mean even kuu had three million selling albums but from what I gathered seiko's impact was more powerful, like seiko is the uta hime of the showa era (while ayu is the heisei one like it was on Music Station last week).

And also, I wonder what status hikki's mom reached fuji keiko/utada junko if she is important to mention. I didn't see she had a million selling release anyway but I remember she had releases that charted many weeks or that were #1 for many weeks and such and I also wonder how many other solo females (or bands with female soloists) that were really popular that we don't know of, if there were any more. Sometimes I wish we had some sort of official list of most popular japanese female soloists of all times, like general list, not necessarily with positions. Of course it should include all the female soloists that were ever popular in Japan, all of them. Doesn't matter if it's pop or enka (sales wise oricon treats both as one).