Luna hails from Planet Mau, advising Queen Serenity throughout the Silver Millennium on the Moon. After the Dark Kingdom annihilates the Moon Kingdom, Luna and her counterpart Artemis enter suspended animation and journey to Earth. Critical memories are sealed to aid their mission: locating and awakening the reincarnated Sailor Guardians while concealing Princess Serenity's identity to avoid premature exposure. Appearing as a small black cat with a crescent moon forehead mark, Luna communicates with humans and materializes magical items essential for Guardian transformations and missions. She first encounters Usagi Tsukino, revealing her destiny as Sailor Moon and granting the initial transformation brooch. Luna guides Usagi to find fellow Guardians—Sailor Mercury (Ami Mizuno), Sailor Mars (Rei Hino), Sailor Jupiter (Makoto Kino), and Sailor Venus (Minako Aino)—coordinating their battles against the Dark Kingdom and later foes. Her technical expertise allows operation of advanced equipment in their underground headquarters beneath Game Center Crown. During the Dark Kingdom arc, Luna's suppressed memories resurface. She accompanies the Guardians to the Moon's ruins, where Queen Serenity's consciousness reveals their past lives and Luna's oath to protect Princess Serenity (Usagi). Luna strategizes against Queen Metaria, urging Usagi to unite Silver Crystal fragments. In the Black Moon arc, she identifies Chibiusa's non-hostile intent and distributes upgraded transformation pens (Star Power Sticks) and communicators to the Inner Guardians. Her role lessens during the Infinity arc as Outer Guardians (Sailor Uranus, Neptune, Pluto) emerge, though she sustains operational support. Luna's personal life evolves through her partnership with Artemis, a white cat sharing her origins and abilities. Their future daughter, Diana, travels from the 30th century, confirming their familial bond. Luna occasionally assumes human form—first during the Queen Metaria battle while praying on the Moon, and later in the Dream arc after Queen Nehelenia's defeat. This form manifests as a delicate girl nearly Usagi's age, with gray-black odango-styled hair and her crescent mark. In non-canonical media like the 2003 live-action series, Luna adopts a human alter ego, Luna Tsukino, who transforms into "Sailor Luna," Guardian of Love and Small Things, via a cell phone-like device. In film adaptations of later arcs, Luna appears human alongside Artemis and Diana during the Dead Moon conflict (Eternal) and the Shadow Galactica battle (Cosmos). Her abilities include teleportation and space survival in human form, though attacks to her crescent mark nullify her powers, reverting her to an ordinary cat. Across all media, Luna's narrative underscores her loyalty, strategic insight, and enduring mentorship of the Guardians.