Umm... All I can do is throw the moonrunes at the pixiv account through a translator, but from what the translator says, this is "Kochiruno"/"Kocirno", which is a pun on Kochiya, obvoiusly, along with Cirno. I'm not sure, but it doesn't seem like an "if they mated", but instead an "adult Cirno stole Sanae's clothes" and "gathered the faith of fools".
If so, adult Cirno is obviously several sizes larger than Sanae in the bust department...
