Yuyuko on her younger years.

I thought that was a microphone in the thumbnail. I can't decide if this is better or not

WestTxTapper said:
I remember reading a doujin (can't remember the title unfortunately) where Yuyuko performed a sword dance with Yukari. It was beautiful.

You have my interest.

jdwdesu said:
You have my interest.

My guess is that he/she is reffering to this doujin:
http://voile.gensokyo.org/res/34727.html
If I am not mistaken, there are 3 parts in total.

And now you have my thanks!