NAMES AND TITLES OF IMPERIAL FAMILY MEMBERS
The Imperial Family of Japan does not have a surname. When a woman marries into the Imperial Family, she loses her surname and takes a feminized version of her husband's title. When Kawashima Kiko married the Emperor's second son, she became "Princess Akishino." Members of the blood who leave the status of Imperial Family member take a surname. Princesses lose their membership in the Imperial Family upon marriage (unless they marry an emperor or an imperial prince) and take the surnames of their husbands. Princes who renounce their Imperial Family membership generally adopt a surname derived from their former title.
The styles of imperial princes and princesses consist of a title followed by a personal name and rank. The literal translation of Akishino-no-Miya Fumihito-Shinnō would be "His lordship of Akishino the Imperial Prince Fumihito." The usual English translations are: Prince Akishino, Prince Akishino-no-Miya or Prince Akishino Fumihito. Titles, such as Asaka, Teru, Hitachi generally derives from geographic regions or Shinto shrines.
The Emperor (Tennō), the Empress (Kogō), the Empress Dowager (Kōtaigo, literally the emperor's mother), and the Grand Empress Dowager (Tai Kōtaigo, literally the emperor's grandmother) are styled His or Her Imperial Majesty (Heika). Imperial princes (Shinnō) and their consorts (Shinnō-hi), imperial princesses (Naishinnō), princes of the blood (ō) and their consorts (ō-hi), and princesses of the blood (Nyoō) are styled His or Her Imperial Highness (Hidenka).
Since the Meiji Restoration, the distinction between Shinnō (and Naishinnō) and ō (and Nyoō) denotes to the incumbent's blood relationship to an emperor. The Emperor's children, the children of the Emperor's sons are Shinnō (in the case of males) or Naishinnō (in the case of females). The Emperor's great grandchildren and more distant descendents in the legitimate male lines are ō and Nyoō, respectively.