Rosie is the reason why Mika has short hair. As a baby, she was a hair grabber. Especially when she started to see color, everyone who didn't have black or brown hair was in danger.
Since Mika was ginger, her hair obviously attracted Rosie's attention. That would not let go and Mika was panicked. She was 12 years old and imagined this was gonna be her life now. Since Val told her to not pull hair away cause it could cut Rosie's skin, her only reasonable solution was to cut the chunk she was holding. Which was a lot.
Lada literally only left for two minutes and returned in horror to see half of Mika's hair was chopped off, Mila with scissors, and Rosie with two fists full of hair. It wasn't a fun day explaining this to her mother.
