Diana is an adorable and pretty talking grey kitten with a crescent moon on her forehead. She is Rini's companion, and the daughter of Luna and Artemis from the future. She only appeared in Sailor Moon Super S.
Diana first appeared in Episode 6, Much Ado About Kitten. Every time Fish Eye saw her (which really only happened twice, the first time in the episode Phony Fairy, and the second time in the episode A True Reflection), she would freak out, as she hates cats.
Diana always seemed clueless as to what was going on.