- - - - - - - - - - /// Luna

Usagi first met Luna when a bunch of boys were bullying the cat on the street.
Luna had a band-aid on her forehead and couldn't talk or investigate while it was
covering the crescent moon there. Usagi was running late to class, but she drove the boys off and rescued
her, taking off the band aid in the process. Once the band aid was off, Luna followed Usagi
around until she was sure that the girl was Sailormoon. Usagi
called the crescent moon on Luna's forehead a "bald spot," and learned
the hard way from Luna to never call it a bald spot again.
Luna is a perfectionist to the core, nagging Usagi to pay more attention to her responsibilities incessantly. Luna is just about Usagi's age, but she seems much more mature. She was once turned into a human in the SailormoonS movie. There was a man named Kakeru that she admired, who got sick. Luna wished that she could be turned into a human so she could be with him and talk to him (the little red bow that she had was a present from him). Her wish was granted by Sailormoon and she got to be a human for a little while. She told Kakeru that his real love was his girlfriend, Himeko, and she also realized that the one for her was Artemis. She also has a human form in the manga for a chapter or two.
Luna has had a crush on Artemis throughout the whole series. It's obvious even though she tries her best to cover it up. She and Artemis are really close and they have a child named Diana in the future. Luna is always teasing Artemis and she would never admit her true feelings. Luna is always focused on her mission and her job, so she really doesn't know about expressing her emotions well. Through their friendship, Usagi teaches Luna how to love. Luna advises Usagi in being a senshi and to be responsible, while in return Usagi teaches Luna how to express her intimate feelings.
- - - - - - - - - - /// Artemis

Artemis
is Minako's white cat and companion. The two fought crime together in England before all
of the other senshi,
so they're real close.
Artemis always flirts with Luna and it's obvious that he loves her. In the Sailormoon S movie, he got jealous of Luna's interest in Kakeru. He and Luna bicker a lot, but that's their sparring emotions. Artemis doesn't have a hard time expressing his feelings to the one that he loves, while Luna's the opposite. When they find out that they have a baby named Diana in the future, Luna is furious because she thinks Artemis cheated on her.
Artemis' job was to revive Minako of her memories and train her as a senshi. He also turned human in the manga to save Minako from falling off a building. Minako and Artemis have a real close relationship. Artemis is the only person who calls Minako "Mina" and he knows when to cheer her up. When she was heartbroken one day, Artemis called to her from a tree and gave her a big bouquet of flowers, asking her if she would like to be her date. Meanwhile Minako, being the psycho she is, always freaks about all kinds of things, and since Artemis lives with her, he has to suffer her tantrums. When Diana came into the picture, Minako was furious that Artemis had never informed her that he and Luna had a baby. He didn't really know, since it was yet to happen in the future, but Minako freaked out anyhow. Poor Artemis.
- - - - - - - - - - /// Diana

Diana
is the tiny gray feline, also the future kitten of Luna and Artemis. She was
given to Chibiusa for a Christmas present by Neo Queen Serenity and King
Endymion. Like Luna and Artemis, she also has a human form, in
which she looks a lot
like Chibichibi.
Diana came from the future as Artemis and Luna's baby, and Luna got furious because she thought Artemis had cheated on her. It was all because of what had happened earlier in that episode. Luna and Artemis were walking down a street when they saw a church. There was a nun, and it looked like Artemis had admired her. Luna didn't quite get mad, but made quite a big deal out of it, letting her jealousy seep through. It just so happened that everyone assumed Artemis fell in love with the nun. When Mamoru took Artemis on a walk, Diana landed in front of them and suddenly exclaimed, "Oh Father! I'm so glad to be here! My mother told me to be careful not to be picked up by strangers!" This caught both Artemis and Mamoru off guard. Another cat that could talk? And she addressed Artemis as father?
It just so happened Luna was walking behind them to apologize to Artemis about making a big deal about the nun, when she saw Diana. She freaked, thinking that Artemis had cheated on her, and slapped Artemis a good one.
It also just so happened that the nun was a target for Tigers Eye. The senshi arrived, destroyed the daimon and saved the nun. They were all standing around in the courtyard of the church talking about the kitty. Diana told Luna and Artemis that they were her mother and father. Luna was shocked, but said stubbornly, "No way. There is no way that I'm going to fall into a relationship with a cat that falls in love with human nuns!" Then Artemis replied (blushing), "No, no! You misunderstood!" (He had been saying that the whole day, and finally people were listening to him) "I didn't fall in love with her! I was just thinking how nice it would be if a cat could be married in such a great place." Luna blushed and everyone started laughing. Artemis told Mamoru that now he knows how Mamoru feels.
Chibiusa recognized the cat because Diana is Chibiusa's pet in the future. Chibiusa always carries Diana on her head (she makes a good hat). Diana is adorable and unpredictable. She says random things, asks off the wall questions without realizing just what she's saying, and catches everyone off guard. She's great comedic relief.