The Sailor Moon metaseries includes three different cat characters who act as advisors to their respective owners. Each has the power of speech, and bears a crescent moon symbol on his or her forehead. The two older cats, Luna and Artemis, lived millennia before the main plot in the Moon Kingdom and acted as advisors to Queen Serenity —the third, Diana, is much younger and was originally born on Earth. Because of this close association with the moon, they are each named after Greek and Roman moon goddesses (even though Artemis the cat is male).
Throughout the series, the cats serve as mentors and confidantes, as well as a source of information and new tools. They are able to advise the Sailor Senshi on their duties, on the history of the Moon Kingdom, and on ancient legends which illuminate the best course of action. In addition, they are able to produce special items that allow the Senshi to awaken, or that strengthen their powers. The feline characters are featured less prominently as the series progresses, but increased emphasis is placed on them as more than counselors. They are shown to have additional physical forms, a deeper backstory, and even an unrequited love or two.
Although Luna takes the largest role of the three, technically Artemis was the first; he figures prominently in Codename: Sailor V, the manga series which preceded Sailor Moon.
Luna (ルナ Runa?) first appears in the first episode or act of every version of the series. In the Silver Millennium, she was a servant to Princess Serenity, sworn never to leave her side, as well as an advisor to the Queen. When the kingdom fell, she and Artemis were put into a long sleep and sent down to Earth to look after the Senshi, who would eventually be reborn there. 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 Guardian Senshi. She found Usagi Tsukino first and taught her to become Sailor Moon, not knowing that this was merely a disguise meant to hide Usagi's true identity as the reincarnated princess. Luna has blue eyes in the manga and live-action series, but red eyes in the anime.
In the manga, anime, and live-action series, Luna provides the Senshi with many of their special items, particularly early on. The items always spring into existence, seemingly out of thin air, and it is unclear whether she is creating them herself or simply producing them from some other location. In the manga only, she demonstrates some other special abilities, such as protecting the Senshi from a deadly attack.
Over the course of the series, Luna develops a close bond with Usagi, though early on it is on uneasy terms, as Luna often upsets Usagi by giving her advice she does not want, often leading to comic results. She also becomes good friends with Ami Mizuno. She and Artemis have an implied romantic relationship, which is confirmed when they meet Diana, who is their daughter from the future. During the Sailor Stars anime, Luna also develops a crush on Kou Yaten, one of the Three Lights.
Luna has a special manga story devoted to her, entitled "The Lover of Princess Kaguya," in which she falls in love with a human named Kakeru. This story was adapted in Sailor Moon S: The Movie, and features Luna's first transformation into human form, which has blue eyes even in the anime.
In the first official Sailor Moon character popularity poll, Luna was the eighth most popular character out of thirty eight choices. One year later, now with fifty choices, Luna was the twenty-second most popular character.
In the original anime, as well as the live-action series, Luna is voiced by Keiko Han, the same woman who voiced Queen Beryl. Her English voice actress for the entire series was Jill Frappier, who portrayed the character with an English accent, described as "fairly old, not to mention cranky and British". Her role in the series has been compared to Rupert Giles' in Buffy the Vampire Slayer.
In the Pretty Guardian Sailor Moon series, Luna and Artemis are portrayed as stuffed toys rather than real cats. Usually they are represented by a puppet, though CGI effects are used for complicated scenes.
In Act 26 of the series, Luna gains the ability to turn into a young human girl, given the name Luna Tsukino, and is able to become a Sailor Senshi. Her 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. She also has heightened hearing and is able to move extremely quickly. Luna involuntarily transforms back into a plushie under certain circumstances such as sneezing, taking a direct attack from an enemy, or falling unconscious.
By dialing 6-7-2 on her Lunatia S (a special cell phone) and shouting "Luna Prism Power, Make up!" she can transform into Sailor Luna, the "Soldier of Love and Small Things." In this form she uses a special attack called "Luna Sucre Candy" which bombards an enemy in exploding sweets. Her main weapon is a "candy" wand, which looks similar to Sailor Moon's "Moon Stick" and which she can transform into various other objects, such as a paper fan or a butterfly net.
In the Special Act epilogue, Luna is the only one of the Senshi who is still able to transform without outside assistance. She is also shown living mainly as a human with Usagi's family, with whom she gets along quite well, though she still takes on her cat form when necessary. She is also shown to have taken on some of the personality traits of Usagi and her mother, such as acting in the same melodramatic manner when waking up in the morning.
The character of Sailor Luna was designed by Naoko Takeuchi herself. One of the only times she appears in an outfit other than those Takeuchi designed—her Senshi 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. Rina Koike thought that she was going to play Chibiusa until she went in for a costume fitting. However, Chibiusa never appears in Pretty Guardian Sailor Moon.
For Luna's plushie form, Keiko Han reprises her original role as the cat's voice. When in human form, Luna is played by Rina Koike.
Artemis (アルテミス Arutemisu?) first appears in Act 1 of the Sailor V manga, Act 7 of the Sailor Moon manga, Episode 33 of the anime, Episode 1 of the dubbed anime, and Act 11 of the live-action series. He is the companion to the leader of the Guardian Senshi—he trained Minako Aino as Sailor V, and remains by her side when she takes on her proper role as Sailor Venus.
His memory of the Silver Millennium seems to be more intact than Luna's—in fact, before appearing in the Sailor Moon series he guides her through the Sailor V video game at the arcade, but not revealing his true identity (and giving the codename "Central Control" in the dubbed anime). When a technical problem reveals him, Luna is greatly annoyed to learn that he's been the one guiding her all along. Later, he fills in the details of her true mission. He has green eyes in the manga and live-action series, but blue eyes in the anime.
Artemis is more easygoing than Luna, and has a "big brother" relationship with Minako, although his attraction to her is sometimes implied. He also cares very deeply about Luna, often comforting her when she is distressed and stating his admiration of her. In addition, he is a good father to Diana as evidenced by her affection for him.
In the Sailor V manga and the live-action series, Artemis gives special items to the Senshi, although unlike Luna he does not seem to produce them himself. He never does this in the Sailor Moon manga or the anime. He also does not seem to mind the fact that he is named after a female goddess, even when teased about it by Minako.
In the first official Sailor Moon character popularity poll, Artemis was the seventeenth most popular character out of thirty eight choices. One year later, now with fifty choices, Artemis was the twenty-sixth most popular character.
In the original anime, Artemis is voiced by Yasuhiro Takato. He is portrayed by Ron Rubin in the English dub with no particular accent, in contrast to Luna. He appears in the first Sailor Moon musical, played by a cat-suited Keiji Himeno. In the live-action series, he is represented as a toy, stuffed cat, and is voiced by Kappei Yamaguchi.
Diana (ダイアナ Daiana?) is the third of the feline characters to appear, though the circumstances of her introduction vary. In the manga, she first appears when the Senshi travel to the 30th century in Act 18. There, she is revealed as the child of Luna and Artemis, and when the Senshi return to the 20th century in Act 23, she goes with them.
In the anime, she does not appear until Episode 133 of the SuperS series, when the grey kitten suddenly jumps out of the bushes, calls Artemis her Daddy, and nuzzles up against him. Artemis is shocked and confused to find out that he has a daughter, while an angry Luna accuses him of an affair with another female cat and scratches him across the face before running off, leaving him alone with a puzzled Diana. Only later it is revealed that Diana has come from the future and that her mother is Luna. In both versions of the series, Diana has pink eyes.
Just as Luna and Artemis guide Usagi and Minako, Diana acts as a guardian to Chibiusa. She is very curious, eager to help, and deeply polite, always addressing Usagi and Mamoru with the Japanese honorific "-sama" and calling Chibiusa by her formal title, Small Lady. She is also able to help the Senshi on occasion, despite her youth, and often because of the knowledge she has gained in the future. In Act 46 of manga, having returned to the future along with Chibiusa, she is able to sense the danger her parents are in and go back in time to save them from being killed.
On one occasion, Diana goes to Sailor Pluto and asks her to go to Sailor Moon's aid. When Pluto tells her she is unable to leave her post, Diana tells her that she will watch it in her place.
In the second official Sailor Moon character popularity poll, Diana was the sixteenth most popular character out of fifty choices.
Kumiko Nishihara provides the voice of Diana for the original anime. She is voiced by Loretta Jafelice in the English-dubbed series, and by Naomi Emmerson for the English Sailor Moon SuperS movie. She does not appear in either the musicals or the live-action series.
In the anime, it is never suggested that the cats are anything but cats, and only Luna ever transforms into a human. In Act 41 of the manga, however, Sailor Moon's power causes her companions to revert to their true forms. The Sailor Senshi become princesses, and the three cats are teleported to Sailor Moon's location, where they take on human forms. Luna's shape is the same as she had acquired previously, Artemis gets reverted to the form he had taken earlier in the arc to save Minako, while Diana is shown this way for the first time. (Both Luna and Diana have odango incorporated into their hairstyles, probably modelled after Usagi.)
The reason for their transformation is not discussed until Act 46 of the manga, in which the three are attacked by Sailor Tin Nyanko. She calls them traitors, using her power to change them once again into humans, and then chasing them and trying to kill them. When she introduces herself to Sailor Moon, Luna realizes who she really is—a false Senshi from their original planet, Mau, which had once been protected by Sailor Mau. Artemis terms it a peace-loving world, but Tin Nyanko informs him that after he and Luna "abandoned" it, its people were wiped out by Sailor Galaxia. At this point, Diana, also in human form, arrives from the future and tries to intervene, but Tin Nyanko hits all three of them with blasts from her bracelets, and they shift to ordinary cats, unable to speak.
Later, as they care for the badly injured cats, Princess Kakyuu tells Usagi that the three of them have powerful starseeds, as brilliant as Sailor Crystals. In Act 47, it is revealed that their inability to speak is a result of injuries to the crescent moon symbols on the cats' foreheads, and before leaving to fight Galaxia, Usagi leaves them in the care of her mother. In the next Act, they are brought to the River Lethe and killed by Sailor Lethe. They are reincarnated at the end of the series with everyone else.
- Takeuchi, Naoko (1992). "Act 9". Bishoujo Senshi Sailor Moon Volume 2. Kodansha. ISBN 4-06-178731-4.
- Takeuchi, Naoko (1993-04-06). Bishoujo Senshi Sailor Moon Volume 3. Kodansha. ISBN 4-06-178744-6.
- Takeuchi, Naoko (1994-07-06). Bishoujo Senshi Sailor Moon Volume 7. Kodansha. ISBN 4-06-178781-0.
- Doi, Hitoshi. "Bishoujo Senshi Sailor Moon". Archived from the original on 2 September 2006. Retrieved 6 October 2006.
- Pretty Guardian Sailor Moon, Act 27.
- DVD Extra: Pretty Guardian Sailormoon Oshiokiyo 25-28
- Episode 37
- As when he spies on her in the shower, with "a lover's eyes." Takeuchi, Naoko (1995). "Act 38". Bishoujo Senshi Sailor Moon Volume 13. Kodansha. ISBN 4-06-178820-5.
- Takeuchi, Naoko (1993). "Volume 2". Codename wa Sailor V Book 1. Kodansha. ISBN 4-06-322801-0.