The Informant:

My friend is someone I met two years ago when I first came to USC. She and I lived on the same floor and had similar classes. She was born in Japan and immigrated to the U.S. when she was less than four years old. She heard this reference when she was visiting her friend back in Japan in high school.

When a girl cuts her hair to make a drastic change, it means she was dumped by her boyfriend or rejected when confessing to someone. 

The Analysis:

The saying falls along the lines of a sort of remedy to channel the girl’s sadness or frustration at rejection. It represents the rejection but also a new beginning that comes after a type of failure. The cutting of one’s hair signifies that one has abandoned the faulty past and is working to move one to the future. The hair is significant because a maiden’s hair is a major form of attraction for men. Cutting off this form of attraction can mean that the boy had no attraction towards the girl so she might as well cut it off. The importance of hair in the Japanese culture accentuates the act of cutting it and this in turn accentuates the meaning behind it.