Mizuira was a little girl with a large smile. She had blonde curly hair, with a ribbon 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 little girl for the family dinner.
Her parents took her out to dinner at a restaurant for her eighth 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 destroyed by Vice Admiral Sakazuki.