Yes, she's actually a cat.
The Star of Cottonland (綿の国星 — Wata no Kuni Hoshi) is a shoujo manga by Yumiko Ōshima that ran in LaLa from 1978 to 1987. It was adapted to an anime movie by Shinichi Tsuji in 1984.
Chibi-Neko is not a human girl with cat ears and a tail. She's a normal kitten, but she wants to be human and imagines herself as such. She is never shown as a cat, only as a toddler girl with long beautiful hair and a frilly dress. And cat ears and a tail.
The story is about her adoption into a human family and her struggles with her identity as a cat. If you don't want anything that deep, it's also a Ridiculously Cute Critter story. Think of Chi's Sweet Home with a big dollop of surreality.
Tropes:
- Become a Real Boy: Chibi-Neko is a cat who wants to become human so much that she envisions herself as a Cat Girl, and is never shown as a real cat. Unfortunately, it's a Tragic Dream for her since Raphael tells her outright that it's impossible.
- Cat Girl: Chibi-Neko is one of the earliest known examples, and is widely considered to be the Trope Codifier. While she's actually just a regular cat, she wants to become human so much that she envisions herself as a human girl with a cat's ears and tail.
- Cram School: Tokio failed his university entrance exams. He's supposed to attend prep school, but he skips without his parents knowing.
- Crazy Cat Lady: Or Man — the neighbourhood cat maniac sits on the fence between this and Kindhearted Cat Lover. On the creepy side, he roams the streets with a net for catching cats. On the nicer side, he takes them home to pamper and care for them in his luxurious apartment.
- Eek, a Mouse!!: Chibi-Neko gives a "present" of a dead mouse to Fumiko. Naturally, Fumiko isn't pleased by this.
- Innocent Inaccurate: Chibi-Neko believes her first family lost her, not abandoned her.
- Nervous Wreck: Tokio's mother, Fumiko, was pretty high-strung to start with out of concern for her son's future. Having a cat around just made her worse.
- Stock Animal Diet: Although Chibi-Neko is a kitten and only drinks milk, she still daydreams about fish.
- Stylized for the Viewer: Chibi-Neko is just a regular kitten and the human characters treat her as one, but she's only ever depicted as a Cat Girl due to her desire to be a human.
- Throwing Off the Disability: Fumiko is said to have an "allergy" to cats, but it seems more like a cat phobia. She forces herself to interact with Chibi-Neko in hopes of conquering her fear.
