No wonder Yukari knows Rinnosuke, she knows him since her younger years.

The possibility that Rinnosuke is older than most touhou girls would be a nice canon. It's still a nice idea.

Rinnosuke first met Yukari in CoLA chapter 11. This image and the iPod are also from that chapter. And yes, Rinnosuke is certainly older than many other characters.

The only thing that seems even remotely wrong with this image to me is that Rinnosuke is NEVER that comfortable around Yukari... and she's just adorable enough here to make that not even matter anymore.