One of the Alts_of_a_Kappa

Note: "Cat Sidhe" is pronounced "KEHT-shee". I may also write it "Ketshi", to make the pronunciation and the fact it is one name clearer.
Note2: The image used here is one I personally commissioned. Do not steal.
Note3: Nekoko is not actually a cat, or even a neko. She is an illusion fairy. That said, she has gained a neko form after being rebirthed by TricksterKitty.

Physical Appearance
Nekoko has the body of a typical high school girl. She tends to wear a yellow outfit with red highlights, including a yellow jester cap and some striped stockings (see image). The "tail" on her outfit is not actually a body part (in her normal form, anyway), but she CAN make it move as though it were one. Not visible in the image, she also wears an amethyst ring on the ring finger of her right hand.
Nekoko has also been known to wear a Cursed Micro Bikini. Consisting of just a few thin strips of fabric, the micro bikini is one of the most revealing possible types of swimsuit, and Nekoko has secured one in yellow. However, hers has a curse on it... more on that under "Special Abilities". She sometimes wears the Cursed Micro Bikini under her regular outfit as well. She doesn't wear it nearly as often now that she's obtained her new watch, though...
Nekoko has a palm-sized, round, yellow gem embedded in the small of her back, which is visible through a small opening in her shirt at all times. Said opening is constantly positioned right over the gem, regardless of how her shirt may move, and mysteriously vanishes when the shirt is taken off. Even when borrowing shirts from others, this opening appears out of nowhere, so the gem is always visible.
Nekoko is also able to summon a pair of pink fairy wings from her back, which also form a barrier over her gem, pinning down anything (or anyONE) that might be on her gem at the time.
Nekoko has started wearing a golden watch. It tells time! It also does other things... more on that under "Special Abilities".

Special Abilities
As mentioned above, Nekoko can summon a pair of pink fairy wings, which, while out, allow her to fly. Flapping is optional, but she usually does, just for appearances.
Nekoko can also summon her "magic wand", an item that started out as a stun baton with a few decorations on it. This "wand" was later upgraded to be able to channel fire, ice, and other elements besides just lightning, and now runs on actual magic.
Most importantly, as an illusion fairy, Nekoko is able to create illusions, either making things appear to everyone as different from what they really are, or directly altering a targetted individual's perceptions to make that person alone see/hear/smell/feel things they shouldn't, or fail to perceive things they should.
Nekoko is able to generate copies of her Illusion Materia (the gem embedded in her back), which allow whoever holds them to use illusions much like hers, though perhaps not as strong.
If someone else gets a hand on the Materia in Nekoko's back, they can not only use that to create illusions just like any other Illusion Materia, but also gain some level of control over Nekoko's body. The exact level of controls depends on the character's strength of will and how willing Nekoko is to do what they try to make her do.
Nekoko is also able to respawn upon death, or despawn and respawn at will, either in the exact location where she died, or from any nearby illusions or any Illusion Materia. For this reason, she likes to give out Illusion Materia to all her friends, so she can "poof" over to them later, and has lots of choice in where to respawn when she dies.
Nekoko's Cursed Micro Bikini turns whoever wears it into a "micro", cutting their scale by a factor of 10 or more. When removed, the effect is reversed, multiplying the person's size by the same amount. However, if Nekoko is wearing it when she respawns from an Illusion Materia, the respawning process sets her to whatever scale the Illusion Materia is at, overriding the curse. This means that if the Materia she spawns from is held by someone at normal scale, she respawns at normal scale, and removing the Cursed Micro Bikini at that point will make her grow huge.
The gem in Nekoko's back doubles as a storage space. She keeps a few random items inside it. There's plenty of room in that interdimensional storage space, but she doesn't really use it for much.
Nekoko has acquired a Revive Materia from Magical_Mindy, that allows her to regenerate those she eats, even if they lack revival methods of their own. Now she can enjoy the taste of cute, friendly people without feeling guilty!
Nekoko's golden watch was a gift from the Godsune_Twins, created to give her a more convenient method of altering sizes than her Cursed Micro Bikini. If she swipes her finger left on the glass, it shrinks her. Swiping right makes her grow. If she swipes forward, then the person in front of her is targeted instead, and grows/shrinks accordingly. Swiping backwards switches the target back to herself.
Nekoko has acquired a Fire Materia from Jenny_James. It makes and manipulates fire. And a Phoenix Fire Materia. It lets her take the remains of a deceased person and bring that person back to life. Like the Revive Materia, but needing to get the remains out of her stomach before use.

Notable History (Pre-Nexus)
"So you're a person's split personality and delusion made manifest by magic and further empowered by a gem of crystalized knowledge..."
The year was 1987. Sakurai Hiroko was your average everyday high school girl... except for one thing. She had a drug addiction. While high on drugs, she would dress up in a silly outfit and pretend to be a fairy, out looking for a way to return to the fairies' home. During one of these drug trips, she met a man with actual magic, who had been to a place where actual fairies lived, and he was more than happy to take her there. When she came down from her high, she realized she didn't belong there, and quickly contacted the man to bring her back.
While Hiroko was safely brought back to her own world, she couldn't forget the world of magic she had seen. The man who brought her there offered to teach her how to use her own magic, which she eagerly agreed to. It turned out she had an affinity for illusion magic, so the man provided her a gem that would help her train to use illusions: an Illusion Materia. This gem housed ancient knowledge on the use of illusion magic, and the moment Hiroko tried to channel her power through it, she created a very convincing illusion of the fairy girl she had spent so many drug-fueled hours portraying.
That's how Nekoko was born.
Hiroko eventually went back to a more mundane life, but her brainchild lives on to this day, and even went on to have a couple kids of her own.
Years later, Nekoko, technically not having parents of her own, got adopted by the goddess Anri_Lowell, who helped teach her the joys of vore. Nekoko was quick to accept both roles, though the prey role seemed to come more naturally to her. Her mother has been trying to train her to be a better predator as well, offering her voreaphile tinies and chances to stomp around in shrunken cities... but it's still a work in progress, and some of her other friends would prefer to see her not go down that path.

Relations
Nekoko's first daughter, Gensou, has her own daughter named Catseye_Iolite (also played by me). But don't you dare call Nekoko a grandmother. She's Iolite's "Nana", and don't you forget it.
Nekoko has a second daughter, Yume_no_Mytyl (also played by me). The father, and a romantic interest of Nekoko's, is Gyukou_No_Yume.
As noted above, the goddess Anri_Lowell is Nekoko's adoptive mother.
Nekoko is good friends with the Plot_Convenience Fairies (also played by me).
Another romantic interest of Nekoko's is Ruby Rose, from the show RWBY. She's met various versions of the girl outside of the Nexus, and loves them all. If you play a version of this character, I would LOVE to RP with you!

Illusion Materia and Other Notable History (within Nexus)
Nekoko has befriended Genny_Gazal, and after following the girl home for some fun, she provided Genny with an Illusion Materia.
Jenny_James also received an Illusion Materia after a bit of fun. They've bonded nicely since then.
Nekoko gave an Illusion Materia to Casey of What_Next, before allowing herself to be eaten, and changing Casey into a shrine maiden version of Ruby Rose, from RWBY... which she accidentally added boy parts to.
Nekoko has left an Illusion Materia with the rather... colorful stage magician, Magical_Mindy.
Vestari expressed great interest in Nekoko's illusion skills, so she was given an Illusion Materia she could use to make her own.
Magical_Mindy gifted Nekoko with a Revive Materia, so she can bring back people she digests.
Sofia_Sidne plugged her smartphone into an Illusion Materia, and somehow downloaded all its data.
Nekoko finally came across RwbyRose, the first version of her favorite adorable cinnamon roll for her to meet within the Nexus. Naturally, she got an Illusion Materia, too.
Nekoko soon learned about RubyRose_, the future version of RwbyRose... who not only still had the Illusion Materia given to her years ago, but had made it into a necklace! This pleased her greatly.
In one of Mindy's random hangouts, Nekoko met the Godsune_Twins. After a bit of chatting, they created the golden watch she now wears.
In another random hangout, Nekoko met Ignitski_Elron, and after playing around with him awhile, she found herself knocked up with the future Iris_Nekoko.
Nekoko had some fun with Nene of Nene_and_Riri (alongside Jenny_James), ending with the tiny girl being absorbed into one of her egg cells. She's due to be reborn as Fairy_Nene any day now.