The Moon Cats are the main Guardians of the Sailor Soldiers. They were originally from the Planet Mau. Luna and Artemis came to the Moon Kingdom to take on the roles of the royal Advisors to Queen Serenity.

After the fall of the lunar kingdom Queen Serenity sent the cats to the future to find and protect Princess Serenity and find and train her four royal guardians.

Artemis was the first to find one of the four members of the Guardian Senshi. He found Minako and told her he would be able to help her become a beautiful warrior. He helped and trained her to become Sailor V and later Sailor Venus,and maintained contact with Serenity's spirit. Artemis later became "Central" and would give Luna the information that she needed.

Artemis is a bit more laid back than Luna and tends to get into trouble. He had to cover his base when Luna discovered he was Central. He once got caught stealing a fish and was berated for it by Luna.

Despite the fact that they started out on the wrong paws he and Luna love each other. He became upset when Luna was smitten by a human in the S movie. In the future he Luna marry and have a kitten named Diana.

He also has a good relationship with Minako. They care about each other and he is one of the very few who calls her Mina in the original. He gave Minako roses when she was realized the boy she liked was in love with another girl. Minako became upset with him when she thought he had fathered a kitten with a different cat and he became disappointed with her when she was dating two men at once. In the Manga he finds her growing to be beautiful and even sneaked a peek of her in the shower. He became human after Pallapalla dropped a rock on him and gave Minako her crystal to become Super Sailor Venus.

Luna first encountered Usagi while Usagi was late for school. Luna somehow came into having a couple of bandaids placed over her crescent moon mark and came into a couple of boys who were abusing her. Usagi scared the boys off and removed the bandaids. Luna wasn't sure at first if Usagi was one of the girls she was looking for due to her crybaby tendancies but after following her around she became certain that Usagi was the sailor soldier of the moon.

Luna gave Usagi her transformation brooch and trianed her to become a warrior and guided her along down the right path. Or she tried to since Usgai would rather go shopping or read comic books, or stuff her face. She also gave Usagi the Luna Disguise Pen and the Crescent Stick/Wand

Luna found and reawoken three of the other Guardian soldiers. She gave the transformation pens to Ami, Rei and Makato and gave Ami her computer. Luna had an easier time training these three than she did with Usagi. She also returned the memories to the five when Ail and En had arrived.

While it was a rough start with Usagi Luna had noticed a growth in her. In the fifth season Luna remarked that she had seen a bit of maturity in Usagi.

Luna is a bit more strict and sensible than Artemis but she has given into a few vices such as eating human treats, letting Shingo pamper her after Sailor Moon told him to be nice to cats, especially Luna and in the fifth season she formed a crush on Yaten Kou.

in the S movie she developed a crush on a young astronomer. She had developed a cold and passed out in the middle of the street. Kakeru rescued her and nursed her back to health. She wanted to be human for him and thanks to Usagi's wish she did turn human and took him to the moon.

She does fall in love with Artemis although they did not share those feelings at first. Some of his antics made her roll her eyes a few times and when Diana arrived she thought he had fathered her with another cat.

Her relationship with Usagi were rocky at times but she cares greatly about Usagi and Usagi loves her in return. Usagi made sure that Luna became a member of the Tsukino household. During the short period when Mamoru broke up with Usagi Luna did her best to cheer up the girl and when the droid Hypnotica put her sleep spell on Sailor Moon Luna went out to find Mamoru and make sure he saves her.

Diana is the daughter of Luna and Artemis and comes from the future. She first appeared in the R manga and is asked to watch over the time gates so that Sailor Pluto could assist the others. In the anime she appeared in the SuperS season and when she first arrived she unintentionaly caused a bit of trouble for her father.

She is Chibiusa's guardian and one of her best friends. She's a very curious kitten. She once wanted to get to know a "fairy" and sniffed her. She noted how the "Fairy" had a fishy smell. She was not aware the "Fairy" was actually Fisheye and she had scared him away.

She has great love and respect for Usagi and Mamoru since they are the future Queen and King of the Earth. In the original anime she addresses them with the Sama suffix. She blames her self for Mamoru's apartment getting trashed by a fire extinguisher and was determined that her king will finish his research work and papers and watched over him. When she felt an older woman disrespected Mamoru she went to confront her. The elderly woman took Diana in and gave her stew.

Diana also has a human form in the manga

Phobos and Deimos are Rei's personal guardians. They originaly came from the planet Coronis and share the names with the moons of Mars. On Earth the take on the forms of crows that live at the Hikawa Shrine

In the anime the appear in a few episodes. They were with Rei when she was introduced to the series and made Luna nervous. They followed Rei when Jadeite threw her into the subspace where all the missing buses and people were. They attacked the youma that held Rei, helping her escape.

When Zoicite came looking for the rainbow crystal that was in Rei's grandpa Phobos and Deimos were there and ready to attack Zoicite while he was on the roof of the shrine.

in the manga they play a bigger part. It was revealed that Rei named them when she first came to the shrine as a little girl and her reasoning was that "Those were their names" and she knew them. They help her by giving her tips such as news articles.

They also have human forms and revealed their human forms the first time when Rei was fighting Tigerseye. They gave her the crystal she needed to become Super Sailor Mars. In the Stars arc they fought against Sailor Lead Crow and was defeated by her.