We are shown her full backstory in her personal story, up including to her wish(which is a wild one), she really is only 17, she is more of a case of someone who has a wide variety in taste and is more prone to enjoy media outside her age range, so she has a tendency to pick up on certain things from it, it's like when you watch Grease and you can't get Summer Nights out of your head for a week.
I know that her Personal Training story jokes about her being older, but it is more joking on how secretive Mitama is about herself despite her otherwise welcoming demeanor, most girls know very little about her other than she is the Adjuster, but she has her reasons to be secretive, mostly tied to her having been through a lot, I did say she was close to Witching out immediately after her wish, for how bad her life was at the time.
last edited at May 14, 2020 8:48PM