Lluna is a small, talking cat with dark purple fur and a distinctive yellow crescent moon mark on her forehead. She originates from the ancient Silver Millennium, the kingdom of the Moon, where she served as a trusted advisor to Queen Serenity and a devoted servant to Princess Serenity. When the Silver Millennium fell, she and another cat named Artemis were placed into a long sleep and sent to Earth, tasked with finding and awakening the reincarnated Sailor Guardians. To protect the princess’s secret identity, part of Lluna’s memory was suppressed during this mission.

Lluna first appears in the early episodes meeting Usagi Tsukino, a seemingly ordinary schoolgirl, and revealing to her that she is the chosen guardian Sailor Moon. She provides Usagi with her first transformation brooch and later helps awaken Ami Mizuno, Rei Hino, and Makoto Kino as Sailor Mercury, Sailor Mars, and Sailor Jupiter respectively. Though initially unaware that Usagi is also the reincarnated Princess Serenity, Lluna remains a constant source of guidance, research, and tactical advice for the team.

Her personality is caring but often strict and serious, which sometimes creates comedic friction with the carefree Usagi. Lluna is intelligent, resourceful, and deeply protective of the Sailor Guardians, especially Usagi. She is also fiercely dedicated to her mission of protecting Earth from evil. Over time, her bond with Usagi grows from a mentor‑student relationship into a close, affectionate friendship. Lluna becomes a member of the Tsukino household, where the family adopts her as an ordinary pet, unaware of her magical nature.

Key relationships include her romantic partner Artemis, a white cat who assists Sailor Venus. Their implied long‑term connection is confirmed when they meet their daughter Diana, who comes from the future and serves as an advisor to Chibiusa. Lluna also develops a close friendship with Ami Mizuno, and in the Sailor Stars arc she briefly shows a crush on Kou Yaten, one of the Sailor Starlights.

As the series progresses, Lluna’s role evolves from a central guide in the first story arc to a supporting figure who continues to provide advice, magical items, and strategic support. In the manga and later adaptations, she gains the ability to take human form, first through the power of the Silver Crystal in a side story where she falls in love with a human named Kakeru, and later on her own. In the live‑action series, she can transform into Sailor Luna, the “Guardian of Love and Small Things,” with a yellow and purple sailor uniform and cat‑like traits. As a human, she retains her cat‑like behaviors and gains abilities such as flight, teleportation, and heightened speed.

Lluna possesses several notable abilities beyond speech. She can materialize magical items for the Sailor Guardians, seemingly out of thin air. She is adept at handling technology, accessing secret bases and arcade machines. Her crescent moon mark is a focal point of her power; if struck, she temporarily loses her abilities. In human form, she can survive in space and teleport herself and others. These abilities underscore her role as a mentor and facilitator rather than a frontline fighter, yet she proves capable of defending herself and the team when necessary.