Luna is a black cat from the Moon Kingdom and the guardian of Princess Serenity in the Silver Millennium. In the present day, she awakens on Earth to guide Usagi Tsukino into becoming Sailor Moon and recruit the other Sailor Guardians. She provides advice, supplies transformation items like the brooches and communicators, and monitors threats from the Dark Kingdom and beyond. Despite her serious demeanor, Luna deeply cares for the girls and occasionally relaxes, such as enjoying fish or playing with Artemis, the white guardian cat and her partner.