Toga Himiko ((#2))

She was taken in by Tomura Shigaraki and All For One at the young age of seven. Shigaraki at the time was thirteen. They then took in Touya Todoroki, who was eleven. The three kids got along well, despite some little mishaps here and there. They became close, like family. Twice joined them about six years later. Kurogiri started working for Shigaraki when he turned 18, and they became good friends.
Her family noticed her missing on day one, and eventually her parents Mitzuki Bakugo, and Masaru Bakugo gave up with police searches. But her older brother Katsuki Bakugo never gave up looking for her. She recently turned fifteen, and met up with her brother again.