r/SheenaRingo

Can someone give me a bit of a background of this cover? I find it interesting that they picked this picture as their cover lol.

i ordered some cds off mercari and got this folded into one of them, does anyone have a similar one or know where it's from at all? i'm assuming it's a store promotional poster since it says not for sale, but i can't find anything about this one online at all. if it's something special i might get it restored for my own collection so that's why i'm wondering.
i should probably also mention it came in the original taiwanese emi release of shoso strip in case that has anything to do with it. could be an extra that came with the original purchase but i have no way of knowing since the original listing just said there was a bonus included, though again i can't find any info about this bonus anywhere else