Eldest brother of former Emperor Hirohito dies at age 100

In this Jan. 2, 2015 photo, Japan's Prince Mikasa waves to well-wishers from a balcony during a New Year's public appearance at the Imperial Palace in Tokyo. The younger brother of former Japanese Emperor Hirohito has died at the age of 100. The Imperial Household Agency announced Thursday, Oct. 27, 2016, that Prince Mikasa died Thursday morning at a hospital in Tokyo. (Kyodo News via AP) (The Associated Press)

In this Nov. 16, 2015 file photo released by Imperial Household Agency of Japan, Japanese Prince Mikasa, right, and his wife Princess Yuriko, left, talk at their residence in Tokyo. The younger brother of former Japanese Emperor Hirohito has died at the age of 100. The Imperial Household Agency announced Thursday that Prince Mikasa died in the morning at a hospital in Tokyo. (Imperial Household Agency of Japan via AP, File) (The Associated Press)

In this June 17, 2014 photo, Japan's Prince Mikasa, right, with his wife Princess Yuriko, center, and Crown Prince Naruhito, left, attends Prince Katsura's funeral service at Toshimagaoka graveyard in Tokyo. The younger brother of former Japanese Emperor Hirohito has died at the age of 100. The Imperial Household Agency announced Thursday, Oct. 27, 2016, that Prince Mikasa died Thursday morning at a hospital in Tokyo. (Yohei Nishimura/Kyodo News via AP) (The Associated Press)

The younger brother of former Japanese Emperor Hirohito died Thursday at the age of 100.

The Imperial Household Agency announced that Prince Mikasa had died in the morning at a hospital in Tokyo.

Japanese media reports say he had been hospitalized since May, initially because of pneumonia. Citing unnamed sources, they say his condition took a sudden turn for the worse on Thursday.

Prince Mikasa was born on Dec. 2, 1915. He is the uncle of the current Emperor Akihito and was fifth in line to the throne.

His brother Hirohito reigned for more than 60 years, during World War II and until his death in 1989.