Naoko Takeuchi’s iconic Magical Girl series, Sailor Moon is known for its glamorous Guardians and equally fashionable villains. The story begins when 14-year-old Usagi Tsukino rescues a black cat from bullies and notices a crescent mark on her forehead. This small act of bravery unlocks Luna’s ability to speak, leading her to reveal Usagi’s destiny as Sailor Moon. Under Luna’s mentorship, Usagi learns to harness her powers and protect the Earth.

Sailor Moon’s heroines may be the Sailor Guardians but they are not the most essential characters for the story. This title must go to Sailor Moon’s loyal cat, Luna. Their bond forms the series’ core, with Luna acting as an unconventional, yet capable, Sensei on Usagi’s journey as Sailor Moon. While she may not have Sailor Guardians’ spectacular powers or stylish costumes, her guidance and mentorship are invaluable to Usagi, teaching her to embrace her powers as Sailor Moon and navigate her destiny.

Luna's Backstory Is Deeper Than It Appears

Greco-Roman Mythology Is Always At the Core of Sailor Moon

Although she appears as an average cat, Luna is a layered character with her own backstory, romantic ties, and even a human form. Luna, along with Artemis, her white cat counterpart, hails from the planet Mau but left to serve the Moon Kingdom during the Silver Millennium. Luna’s name honors the Roman Moon goddess, Luna, a counterpart to the Greek Goddess, Selene, the inspiration for Princess Serenity. After Serenity’s death, Luna was sent to Earth to guard and guide Usagi, the princess’s reincarnation.

She provides Usagi with essential tools like the Disguise Pen and serves as both a mentor and a friend. Luna’s role is vital, giving Usagi the confidence and direction she needs to fulfill her destiny. Although a side character, Luna is given surprisingly poignant moments. In Sailor Moon S: The Movie, her brief romance with a human astronomer becomes a central plot point, revealing Luna’s hidden depth.

Mau is the Ancient Egyptian word for cat, and the inspiration for Luna and Artemis' home planet.

While this romance is short-lived, she ultimately builds a lasting partnership with Artemis. Sailor Moon Cosmos further explores Luna’s history when the villain Sailor Tin Nyanko—a fellow cat from Mau—harbors resentment toward Luna and Artemis for their devotion to Usagi, accusing them of abandoning their home planet. This personal connection adds deeper motives to Tin Nyanko’s actions in addition to harvesting Usagi’s Sailor Crystal.

Luna And Artemis Awaken the Sailor Guardians

Sailor Moon's Other Power Couple Make a Great Team

Without Luna, Sailor Moon wouldn’t have awakened, and without Artemis, Luna’s task would have been impossible. In the series’ first arc, Luna receives missions through “Central Control,” which is later revealed to be Artemis in disguise. Although Artemis curiously conceals his identity and waits to introduce Sailor Venus to the group, he’s every bit as capable and dedicated as Luna is. Acting as a big brother to Minako, Artemis provides romantic advice and moral . While clumsy and lazy at times, Artemis' character balances Luna’s intensity, and the two of them are stronger for it.

Artemis and Luna’s relationship adds levity to the series, especially when Artemis grows jealous of anyone who attracts Luna’s attention. However, he’s more than just comic relief. In Season 2, Episode 33, “Artemis’ Adventure: The Monster Animal Kingdom,” he discovers Esmeraude’s plot to hijack an animal shelter for the Black Moon Clan. In a brave moment, Artemis allows himself to be whipped by Esmeraude’s Droid to shield Luna. Although Sailor Moon and Venus eventually rescue him, Artemis’s courage shines through, cementing him as more than a ing character but as a vital part of the series’ emotional core.

Diana Will Advise the Next Generation of Sailor Guardians

Just Like Chibiusa, Diana Is Wise Beyond Her Years

Luna and Artemis cement their relationship with the creation of their daughter, Diana, a gray kitten with her own human form. Diana becomes Chibiusa’s mentor, much like Luna mentors Usagi. Named after another Roman Moon goddess, Diana is respectful, curious, and wise beyond her years, fitting perfectly alongside Chibiusa. In the series’ final arc, Princess Kakyuu reveals that the Star Seeds of Luna, Artemis, and Diana shine nearly as bright as Sailor Crystals, a testament to their strength and loyalty. The cats even use their human forms to the battle against the series’ final foes.

From her first introduction, Chibiusa carries a cat-themed spherical device called Luna-P, which helps her navigate her surroundings, likely a relic from before Diana’s existence. Luna-P looks to be inspired by Luna’s physical appearance and symbolizes Chibiusa’s simultaneous need for caretaking and precocious independence. Floating alongside her and transforming into helpful objects, Luna-P underscores the essential role of the feline companions in ing the Moon Kingdom’s royal family.

While the first appeal of the Sailor Moon franchise is clearly the glamorous group of Sailor Guardians, the role played by Luna is often underrated. Without Luna’s influence, the series’ events might never have unfolded, potentially leaving the galaxy vulnerable to evil.