I removed these two examples from Important Haircut, since they didn't belong there. No cutting involved, no change in hair length whatsoever. They look like they might belong here instead.
Somewhat inverted in Suzumiya Haruhi: The title character comes to school with a different hairstyle and different color hair ribbon every day, until Kyon catches her attention by sarcastically asking her if she's doing it to confuse the space aliens. Haruhi responds by explaining that she has a theory that each day has a color. She cuts her waist-long hair to shoulder length the next day and from then on sticks with the same hairstyle, letting it mostly loose and using a yellow ribbon on it; it is insinuated that this is because he was the first person to comment on it, although her motivation is never fully explained.
The motivation is hinted at in the second season episode "Bamboo Leaf Rhapsody": it's the same style ribbon with a shorter version of the haircut that Haruhi had three years ago, when she first met time-traveling Kyon on Tanabata.
After almost rewriting the world, but stopped by Kyon, she wear her hair as a ponytail the next day, because Kyon commented in what she thought was a dream, that he liked it when she had her hair that way.
In the anime version of The Sigh of Haruhi Suzumiya, we see Haruhi tying her hair in a ponytail when Kyon enters the clubroom to reconcile with her after their big fight, which she is very depressed about. (In the novel she unties it instead.)
In Akane's first appearance in Mai-HiME, she's seen wearing a barely noticeable ponytail. Several episodes later, when she shows off her CHILD against an Orphan attacking Kazuya and Miyu, the string binding her ponytail falls out, giving her a more mature look (and thus bringing her to terms with her own desire to protect). This is the last we see of Akane for a good while, as immediately after the Orphan is defeated, Miyu skewers the CHILD, effectively eliminating both Akane and her boyfriend from "the game" to occur later in the show. The change seems to have made it across continuities, as Akane from Mai-Otome is first introduced sans ponytail.
I removed these two examples from Important Haircut, since they didn't belong there. No cutting involved, no change in hair length whatsoever. They look like they might belong here instead.