Have some Hiroko Yakushimaru that isn't AS rare but I still had a similarily bad time finding.
What a search that was, it brought me all over the place.
Including the embed.
Which was kind of funny. I searched for this particular song for so long, too.
I had it incorrectly labelled as an "Anri" song (according to the filename when I got it back in the days), and this, too, haunted me for decades.
And then, through piecing together a bunch of puzzles, I finally arrive at the embed.
It was like following a rainbow with a pile of shit at the end instead of gold.
But I found the song and the album and for anyone interested:
https://files.catbox.moe/y3u74s.7z
>>7974
Is another Mika Kanai song, by the way.
Vinus Tanjou, from the not stellar but stylish "Idol Project" OVAs.
Which I recommend because it's pretty cool. It's dumb, but it has animation and an extremely "90s anime" style.