Hitagi, the main female character of Bakemonogatari, is a weak-looking girl with an “incurable disease.” She is in the same class as Koyomi, but he has almost never heard her speak. When she was in the first year of high school, she encountered a mysterious crab, after which she became nearly weightless. Ever since then, she has avoided contact with everyone else, threatening everyone who discovers her secret. She called herself a tsundere and always speaks in an abusive style.
At the end of Mayoi Snail, she admits that she loves Koyomi, and subsequently enters into a relationship with him.
After the events in Tsukihi Phoenix, she overcomes all of her trauma, and becomes a rather cheerful and normal girl. She starts calling Araragi with a cute nickname, chuckling at small things and sending e-mails full of emoticons, although her sharp tongue is still there, but toned down.
She also seems to have a father complex as she becomes excited to the point of being unable to fall asleep when using her father’s blanket.