Senketsu

Senketsu is a sentient sailor uniform and one of the central figures of Kill la Kill, created by Souichirou Kiryuuin (better known under the alias Isshin Matoi) specifically for his daughter Ryuuko. Woven with her DNA, he can only be heard and properly worn by her.

Despite being an article of clothing, Senketsu shows remarkably human qualities: composed and analytical mid-battle, he offers Ryuuko tactical advice and warns her when she's about to run out of strength, while also caring for her with an almost paternal devotion and feeling lonely whenever she isn't wearing him. Being washed by hand terrifies him, while ironing is something he finds oddly soothing.

Found by Ryuuko among a pile of clothes in her late father's laboratory, Senketsu initially needs her blood to stay active until she overcomes her embarrassment and achieves full synchronization with him. Together, the two stand against Satsuki Kiryuuin and, later, far more dangerous enemies.