What episode does the white cat appear in sailor moon?

You're likely thinking of Luna, Sailor Moon's talking black cat companion. There's no white cat that plays a significant role in the original *Sailor Moon* anime.

However, there are a few possibilities:

* Diana: In the *Sailor Moon Crystal* anime, Luna has a white cat counterpart named Diana, who is the companion of Sailor Uranus and Sailor Neptune.

* Artemis: In *Sailor Moon S* and later seasons, Luna has a male cat companion named Artemis, who is black with white markings.

If you can provide more details about the white cat you're thinking of, I might be able to help you pinpoint its appearance more accurately!