Question: Who was Empress of Japan prior to Empress Michiko, the current Empress?

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).

Masako, Crown Princess of Japan: Masako, Crown Princess of Japan (皇太子徳仁親王妃雅子 , Kōtaishi Naruhito Shinnōhi Masako ) , born Masako Owada (小和田雅子 , "Owada Masako" ) on 9 December 1963, is the wife of Naruhito, Crown Prince of Japan, who is the eldest son of Emperor Akihito and Empress Michiko and the heir apparent to the Chrysanthemum Throne.  She is a member of the Imperial House of Japan through marriage.  Should the Crown Prince ascend the throne as expected upon his father's abdication, Masako will become empress consort.

Sayako Kuroda: Sayako Kuroda (黒田清子 , Kuroda Sayako , born 18 April 1969) , formerly Sayako, Princess Nori (紀宮清子内親王 , Nori-no-miya Sayako Naishinnō ) , is an imperial Shinto priestess of the Ise Grand Shrine, currently serving as the Supreme Priestess.  She is the youngest child and only daughter of Emperor Akihito and Empress Michiko of Japan.

Chiso: Chiso Co., Ltd. is a traditional Japanese textile producer, one of the oldest yūzen coloring companies in Nishijin district of Kyoto founded in 1555.  It produces many styles of kimono and the customers include the royal family members Empress Michiko, Princess Akishino, etc.

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.

Mieko Kamiya: Mieko Kamiya (神谷 美恵子 , Kamiya Mieko , January 12, 1914 – October 22, 1979) was a Japanese psychiatrist who treated leprosy patients at Nagashima Aiseien Sanatorium.  She was known for the translation of books on philosophy.  She worked as a medical doctor in the Department of Psychiatry at Tokyo University following World War II.  She was said to have greatly helped the Ministry of Education and the General Headquarters, where Supreme Commander of the Allied Powers stayed, in her role as an English-speaking secretary, and served as an adviser to Empress Michiko.  She wrote many books as a highly educated, multi-lingual person; one of her books, titled "On the Meaning of Life" ("Ikigai Ni Tsuite" in Japanese), based on her experiences with leprosy patients, attracted many readers.

Naruhito, Crown Prince of Japan: Naruhito, Crown Prince of Japan (皇太子徳仁親王 , Kōtaishi Naruhito Shinnō , born 23 February 1960) is the elder son of Emperor Akihito and Empress Michiko, which makes him the heir apparent to the Chrysanthemum Throne.

Empress of Japan: Empress of Japan or Japanese Empress means a female imperial ruler (女性天皇 , josei tennō ) .  The term can also mean an empress consort (皇后 , kōgō ) .  The current empress consort is Empress Michiko (7 January 1989 – ).

Tae Ashida: Tae Ashida (芦田 多恵 , born July 3, 1964) is a well-known fashion designer who has designed many uniforms in high-profile businesses and venues across Japan.  She is the daughter of Japanese fashion designer Jun Ashida who at one point of his career was the dressmaker of Empress Michiko.

Kiko, Princess Akishino: Kiko, Princess Akishino (文仁親王妃紀子 , Fumihito Shinnōhi Kiko ) , born 11 September 1966 as Kiko Kawashima (川嶋紀子 , "Kawashima Kiko" ) , is the wife of Fumihito, Prince Akishino, the second son of Emperor Akihito and Empress Michiko of Japan.  She is also known as Princess Kiko.

Supporting paragraphs: Empress of Japan Empress Michiko
Answer: Empress Nagako