Who knows? If it is, it isn't canon. Last I recall, Satoshi was stinking up a plastic bag a few towns over, and that's from outside the time-loop, so its pretty definite.
Tenebrous said: By Rina I assume you mean Rena? I don't remember that, but like you said, it's Higurashi, so there's no point for me to over analyze it. -_-
I don't think so Rina was Satoshi/Satoko's uncle's mistress
It's explained in one of the tips that it was rina, the lover of both reena's dad and satoko's uncle
There is more than one corpse in there, and since shion-mion looks younger it might be related to tone of the manga exclusive arcs (the one that got canelled) that or it is from the kataribanashi.
That is probably Shion in the picture. She tends to get a bit more bloody than Mion. I don't think Mion has even gone on a rampage. It was always Shion acting as Mion.