Japan's Emperor Akihito arrives at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )

Japan's Emperor Akihito and Empress Michiko arrive at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )

Japan's Emperor Akihito and Empress Michiko arrive at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )

Japan's Emperor Akihito and Empress Michiko arrive at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )

Japan's Emperor Akihito and Empress Michiko arrive at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )

Japan's Emperor Akihito and Empress Michiko arrive at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )

Japan's Emperor Akihito and Empress Michiko arrive at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )

Japan's Emperor Akihito and Empress Michiko arrive at Kyoto Station in Kyoto on March 25, 2019. Imperial Couple will attend a tea ceremony for 30th anniversary of Emperor Akihito's enthronement. The Emperor's abdication will be on April 30, 2019, and his eldest son, Crown Prince Naruhito's succession to the throne on the following day May 1st. ( The Yomiuri Shimbun via AP Images )