Mizuira was a little girl with a large smile. She had light colored, curly hair with bows in it.
Very little is known about her personality, but it is evident that she was not close to her cousin Robin as she did not complain when her mother refused to bring the girl along for the family dinner.
Her parents took her out to dinner for her birthday. Roji wanted it to be a private affair so they did not bring Robin along with them. She is assumed to have died after the escape ship was blown up by Vice Admiral Sakazuki.