Head of her own criminal defense law firm, Mia Fey is Phoenix's boss and mentor.

Always cool under pressure, Mia Fey is smart, tenacious, a strict teacher, and sometimes even coy. She has a great affection for her sister but is also very independent, and strives to uncover truth at all costs.

She seems to have a problem with names, calling Naruhodou as "Naruhodo," and Yahari as "Yappari."

In the original script Turnabout Sisters was going to be the first case, but the writers changed their mind, so that Mia would be able to interact with Phoenix more as his mentor before that case occurred.

Mia has a younger sister, Maya, who she's very close to despite their age difference. Her mother Misty has been missing for 15 years, but she has an aunt, Morgan, and a cousin, Pearl. She is also Diego Armando's girlfriend. He was her mentor in law and a few weeks after the Terry Fawles case that traumatized her so badly,the two started dating. It is unknown how far they were in their relationship, but their love for each other is more than obvious.

Name Origin
English: "Fey" was probably chosen as a last name because of it's connection to magic/spiritualism (as in, Morgan le Fey). Mia was probably chosen to go with Maya.

Japanese: The name "Chihiro" the creator describes as being a pun; the kanji together mean "1000 questions," meaning, "If I have to ask him 1000 times, I will!" The second kanji is also the first kanji in "Cross examination."