Ryūko Matoi is the daughter of Isshin Matoi and the main protagonist of Kill la Kill. She transferred to Honnōji Academy searching for the twin of her red Scissor Blade and the person who used it to murder her father.
It is later revealed that she had supposedly died after a failed experiment to fuse her with Life Fibers and is the younger daughter of Ragyō Kiryūin and sister of Satsuki Kiryūin.
Ryūko has a relatively simple personality: fierce and stubborn. She fears little, which is demonstrated when she directly and disrespectfully addresses Satsuki Kiryūin, demanding that her questions be answered, and when she fights Takaharu Fukuroda even though she is clearly overpowered. Later on she is shown to be quite embarrassed when she is forced to fight in Senketsu's very revealing alternate form, though she overcomes her embarrassment in Episode 3 showing that while she is not afraid of fighting to her death, she is somewhat self-conscious.
She shows fierce determination in finding her father's killer. Her stubbornness was taken up to ridiculous levels when she managed to free herself from Ragyō's mind control by merely punching herself. This same episode, however, has one of few demonstrations of shock on her part, when Ragyō defeats Satsuki, rips out Ryūko's heart and reveals to be her mother.
When Ryūko is brainwashed after being forced to put on Junketsu by Ragyō, her personality changes to be wild and sadistic, destroying everything around her without reason. After she is freed she goes back to her usual personality, but is somewhat calmer and more mature. She also makes peace with Satsuki and is able to fight with her as a comrade, but is still having trouble recognizing her as her sister. Although, after Satsuki catches her when she is falling back to earth and welcomes her home warmly, Ryūko replies by calling her "sis."
- Ryuko will meet Sonic and his friends in Sonic Storm Adventures of Kill la Kill and falls in love with Jak, but she has gotten over it at the end of the series because she can't hurt Keira's feelings.
- Ryuko will meet Team Robot in Team Robot & The Mighty Morphin Power Rangers The Movie & will be guest starring in Emerl's Adventures Of Power Rangers Megaforce & Super Megaforce
- Ryuko will meet the Weekenders in Weekenders Adventures of Kiki's Delivery Service