Who was Prince Hisahito of Akishino's great grandmother?
Prince Hisahito of Akishino: Prince Hisahito of Akishino (悠仁親王 , Hisahito Shinnō , born 6 September 2006) is the youngest child and only son of Fumihito, Prince Akishino and Kiko, Princess Akishino. Prince Hisahito of Akishino:  He is the only grandson of Emperor Akihito and Empress Michiko.
i don't know