I'm going to guess so, as a show of determination. Also occurs in Mononoke Hime (Ashitaka cuts his topknot off before leaving his village) and in Genjitsu Shugi Yuusha (Liscia cuts her long hair off dramatically with a sword).
As for girls, sorry, but I'm in team ninja girl.
https://apogee.polaris-1.work/media/925/blob