Rio

Nina's pet cat, Rio (called 'Leo' in the English translation of the manga) can change into the form of a little boy, with a magic candy. In the anime, all he has to do is a flip and he becomes human. In the anime, he starts to like Ayu's dog, Tamako. His seiyū in the TV series was Reiko Takagi. In Geneon's English dub, he was voiced by an uncredited Mona Marshall. [Source - Wikipedia.]