Hmm.. it looks like the Nendoroid for Azusa from K-ON! has cat ears too.. [link] and it seems you can actually put them on other Nendos. Which is pretty cool. ~ The ones I have for BRS in the picture isn't from her but from Ritsu.. [link] and it's not attachable to others. So.. I just placed it on top of BRS and.. yeah. Lol.