Einhart's friend Yumina Englave informs Fuuka about the circumstances that led to Rinne's current demeanor. Four years ago, Rinne was adopted into the Berlinetta family, receiving the device Scuderia made by her adoptive grandfather. However, as Rinne became popular in her new school due to her athletic potential, she became the target of bullying. Then one day, the bullies became more violent towards Rinne, mistreating her device and preventing her from answering an emergency call as her grandfather ended up passing away. Blaming herself for her grandfather's death, Rinne took brutal revenge on her bullies, becoming determined to become stronger. (thetvdb.com)