In the last episode of the anime, Sakaki apologizes to it for trying to pet it all the time without taking its feelings into account. After that dialogue, it walks up to Sakaki and seemingly allows her to move her hand toward its head as though to pet it, but suddenly then bites her without any warning.
It also gathered a small horde of cats in order to attack Sakaki and Chiyo, but that ploy was foiled by Maya, Sakaki's pet Iriomote Mountain Cat.
Is Kamineko really a jerk and a bully, or is there some deeper reason behind its biting?