The ones on that page say "addon"?  Ruru addon for V4 and Ruka addon and Ruka2 addon for A4.

I have downloaded them, but they do not look like the renders.  After investigating, it seemed there may have been an original Ruru and Ruka, and these are addon's to those originals?

I found this link, looking for the same, and they came to the same conclusion:  LINK

This Manihoni post seems to infer the character was part of a competition?  Link