My guess is that since she hates west people it means her mom is from towa but she was an unwanted child and her mom not accepting her decided to abandon her or kill herself. Inuzuka says that Leon wasn't like that in middle school which implies she discovered her origins and everything else in the time they were apart causing her that great change in personality. Well, that or she and her parents were ostracized for being from different sides and something happened caused by the West giving place to her hatred for them.