From my understanding, the Sex Berry is supposed to change the sex of your pet. About a week ago, I adopted a female Glacier Montre. I then bought a Sex Berry and fed it to her. It showed up on her foods eaten, http://subeta.net/pet_extra.php?act=food&&petid=920935 , but she's still female when she's supposed to now be male.

You have to use it on them, not feed. Feeding just makes it fuller. Using it changes the pet's sex.

Well that's frustrating, and a waste of 28k. Oh well, thanks.