Miharu Hirota

"Before continuing on with a bunch of spoilers, you may want to read Kazuki Hakei's Origin Story."

Kazuki Hakei
Miharu is Kazuki's friend and classmate from his hometown Psemata. She is fairly protective of him, having been part of his main support system while his parents' relationship was falling apart, and they stay in touch through letters even after Kazuki runs away from home.