This page implies that poor Mirai learned how to say "sorry" before any other word in Japanese... Poor girl
Sachiko: Well, to put it simply: this girl's been through a lot of Clanhouses just trying to get her papers sorted, but, literally, no one will take her case...
But that's where YOU come in!
Nozomi: Me, huh... Tell me, have you considered writing to HQ about this error?
Mirai: S-sorry [In English] I don't speak Japanese. Maybe English? I can do that...