Luna is a small black cat with a crescent moon marking on her forehead who serves as the mentor and advisor to Usagi Tsukino, also known as Sailor Moon, and the other Sailor Guardians. In Sailor Moon SuperS, the fourth season of the original anime, Luna continues to provide guidance and strategic support as the team faces the Dead Moon Circus. Her role is consistent with previous seasons: she helps the Guardians understand their mission, offers advice, and supplies them with magical items needed for transformation and combat. However, SuperS places a stronger emphasis on her personal life, particularly her relationship with Artemis, a white cat who serves as Sailor Venus's advisor, and their daughter Diana, who travels from the future to assist Chibiusa. This family dynamic adds depth to Luna's character, showing her as a devoted partner and mother.

Luna's background originates from the ancient Silver Millennium, where she was a servant to Princess Serenity and an advisor to Queen Serenity. After the Moon Kingdom fell to the Dark Kingdom, she and Artemis were placed in a long sleep and sent to Earth with the mission of finding and awakening the reincarnated Sailor Guardians. Part of her memory was suppressed to make this task easier, so she initially does not realize that Usagi is the reincarnated princess. Throughout the series, Luna develops a close, sometimes comedic bond with Usagi, often scolding her for laziness while also caring deeply for her safety. She is intelligent, organized, and disciplined, but also has a vulnerable side, shown in her quest for love and her occasional childish behavior with Usagi.

Motivationally, Luna is driven by her sense of duty and loyalty to the Moon Kingdom and its princess. She is determined to protect Earth and ensure the Sailor Guardians fulfill their destiny. In SuperS, her motivations also include protecting her new family, as she becomes more invested in her relationship with Artemis and the arrival of Diana. Her notable abilities include the power of speech, which only she, Artemis, and Diana share, and the ability to materialize magical items such as transformation brooches and communication devices. She can also transform into a human form, though in the original anime this is seen only in the Sailor Moon S movie rather than in SuperS itself. In SuperS, her primary function remains that of a strategic advisor and emotional anchor for the younger Guardians, especially Chibiusa, who is the focus of this season. Overall, Luna's character in Sailor Moon SuperS blends her unwavering dedication to her mission with a more personal journey involving love and family.