Question: Who was Prince Hisahito of Akishino's great grandmother?

Context paragraphs:
Empress Michiko: Michiko (美智子 ) , born Michiko Shōda (正田美智子 , Shōda Michiko ) on 20 October 1934, is the Empress of Japan as the wife of Akihito, the current Emperor of Japan reigning from 7 January 1989.  She succeeded her mother-in-law, Empress Nagako (Kōjun), consort of Emperor Hirohito (Shōwa).

Shin Hpa of Pagan: Shin Hpa (Burmese: ရှင်ဘား , ] ) was a queen consort of King Narathihapate of the Pagan Dynasty of Burma (Myanmar).  She was the mother of King Kyawswa of Pagan; the paternal grandmother of King Uzana I of Pinya and Queen Saw Hnaung of Sagaing; and a great grandmother of King Swa Saw Ke of Ava.  Through Uzana, she was an ancestor of Toungoo kings Mingyi Nyo, Tabinshwehti and Nanda.  Through Saw Hnaung, she was an ancestor of Sagaing kings from Kyaswa to Tarabya II as well as King Thado Minbya of Ava.  Through Swa Saw Ke, she was an ancestor of Ava kings from Swa to Thihathu, as well as Toungoo kings from Bayinnaung to Mahadhammaraza Dipadi.

Anna Karlsdotter: Anna Karlsdotter (Vinstorpa) (died 1552), was a Swedish noble and landholder.  By her daughter Ebba Eriksdotter Vasa, she was the maternal grandmother of queen Margaret Leijonhufvud and thereby great grandmother of king John III of Sweden and king Charles IX of Sweden.  She is remembered as one of several possible people later identified with the famous legend of Pintorpafrun.

The Half Brother: The Half Brother (Norwegian: Halvbroren ) is a 2001 novel by the Norwegian writer Lars Saabye Christensen.  The story follows a man who grows up in Oslo after World War II, with his mother, grandmother, great grandmother and half brother.  The novel was published in Norwegian by Cappelen in 2001, and in English for the first time in 2003.  It received the Brage Prize and the Nordic Council Literature Prize.  A television series based on the novel was broadcast on NRK in 2013.

Princess Mako of Akishino: Princess Mako of Akishino (眞子内親王 , Mako Naishinnō , born 23 October 1991) is the first child and oldest daughter of Fumihito, Prince Akishino and Kiko, Princess Akishino, and a member of the Japanese Imperial Family.  She is the eldest grandchild of Emperor Akihito and Empress Michiko.

Princess Ingeborg of Denmark: Princess Ingeborg of Denmark ("Ingeborg Charlotte Caroline Frederikke Louise"; 2 August 1878 – 12 March 1958), was a Princess of Sweden by marriage to Prince Carl, Duke of Västergötland.  She was the daughter of Frederick VIII of Denmark, and the maternal grandmother of Harald V of Norway, Baudouin and Albert II of Belgium, and the female line great grandmother of Henri of Luxembourg.

Princess Kako of Akishino: Princess Kako of Akishino (佳子内親王 , Kako Naishinnō , born 29 December 1994) is the second daughter of Fumihito, Prince Akishino and Kiko, Princess Akishino, and a member of the Japanese Imperial Family.  She is the second-eldest grandchild of Emperor Akihito and Empress Michiko.

Louisa Hamilton, Duchess of Abercorn: Louisa Jane Hamilton, Duchess of Abercorn, VA (née Lady Louisa Jane Russell) (8 July 1812 – 31 March 1905) was the wife of James Hamilton, 1st Duke of Abercorn, and the daughter of John Russell, 6th Duke of Bedford, by his second wife, Lady Georgiana Gordon.  She was the mother of Louisa Montagu Douglas Scott, Duchess of Buccleuch, and therefore the paternal great grandmother of Princess Alice, Duchess of Gloucester, and the maternal 2nd great-grandmother of Prince William of Gloucester and Prince Richard, Duke of Gloucester.  She was also the mother of James Hamilton, 2nd Duke of Abercorn, and therefore the paternal great-grandmother of Cynthia Spencer, Countess Spencer, and the paternal 3rd great-grandmother of Diana, Princess of Wales, and the maternal 4th great-grandmother of Prince William, Duke of Cambridge, and Prince Harry.  Through her daughter Lady Louisa Hamilton she also is the maternal 3rd great-grandmother of Sarah, Duchess of York.

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.  He is the only grandson of Emperor Akihito and Empress Michiko.  Hisahito is third in line to become Emperor of Japan, after his uncle Naruhito and his father.

Khongirad: The Khongirad (Mongolian: Хонгирад/Khonghirad), also known as Qongirat was one of the major divisions of the Mongol tribes. Variations on the name include Onggirat, Ongirat, Qongrat, Khungirat, Kungrad, Qunghrãt, Wangjila (王紀剌), Yongjilie (雍吉烈), Qungrat, and Guangjila (廣吉剌) in Chinese sources.  Their homeland was located in the vicinity of Lake Hulun in Inner Mongolia and Khalkha River in Mongolia, where they maintained close ties with the ruling dynasties of northern China.  Because the various Hongirad clans never united under a single leader, the tribe never rose to great military glory.  Their greatest fame comes from being the primary consort clan of the ruling house of Genghis Khan's Mongol empire.  Genghis Khan's mother, great grandmother, and first wife were all Khongirads, as were many subsequent Mongol queens and princesses.  During the Yuan dynasty they were given the title Lu Wang ("Prince of Lu"), and a few Khongirads may have migrated west into the territory of modern Uzbekistan and South Kazakhstan Province.

Supporting paragraphs: Prince Hisahito of Akishino Empress Michiko
Answer: Empress Nagako