She is a black cat who has the ability to talk, and serves as a mentoring figure for the titular character and her companions, the Sailor Guardians.

Luna makes her debut in the first act or episode of each version of the series, in which she meets Usagi Tsukino and tells her she is Sailor Moon, and gives her a brooch that allows her to transform.

Part of Luna's memory was suppressed, in order to make her task easier; she only knew that she was supposed to find and awaken the Sailor Guardians of the inner Solar System.

[10] Even when Luna does not have as many incarnations and special powers as the Sailor Guardians and Tuxedo Mask, she nonetheless manages to get some transformations, as well as a long lifetime virtually spanned between the Silver Millennium era and the 30th century.

The character is first shown to get the ability to transform into a human being in the manga special The Lover of Princess Kaguya, which was released a month after the end of the third arc of the series.

At first, Kakeru thinks this woman is Kaguya, but then he notices Luna's crescent moon mark in her forehead and realizes it is her.

Luna's personality as a human girl is essentially identical to her normal self, except that she has a mild obsession with sweet foods and behaves more like a real cat, in that she runs from dogs and is easily distracted by toys.

Luna involuntarily transforms back into a plushie under certain circumstances such as sneezing, taking a direct attack from an enemy, or falling unconscious.

[11] Luna loses all of these powers if the crescent moon mark on her forehead is hit by an attack, as shown when she, Artemis, and Diana are struck by Tin Nyanko, which renders them as normal cats.

[6]: Act 54  It is also stated by Princess Kakyuu in the final arc that Luna's Star Seed is almost as powerful as a Sailor Crystal.

[2] In this form, she uses a special attack called "Luna Sucre Candy" which bombards an enemy in exploding sweets.

One of the only times she appears in an outfit other than those Takeuchi designed—her Guardian uniform or her purple shirt and yellow skirt—is in the Special Act, where she serves as the flower girl at Usagi and Mamoru's wedding.

Ryō Hirohashi has voiced Luna in all media following Sailor Moon Crystal, while Michelle Ruff has portrayed the character in the English dub of this version.

"[28] However, on a review of a later act, the author praised the "growing friendship between Luna and Usagi", and how the latter defended the former when the brainwashed Mamoru attacked her.

[29] In her review of the season finale, Sullivan stated that voice actress Ryo Hirohashi "did an amazing job expressing helplessness and despair as Luna watched Metalia steamroll over everyone and everything back on Earth.

[35] In the second episode of RuPaul's Drag Race: UK Versus the World, American contestant Mo Heart's look for the "Kitty Girl" runway theme was as Luna, which according to Andy Swift from TVLine, was among the most incredible of the week.