Princess Mikasa, the oldest member of Japan’s royal family and great-aunt to the emperor, died aged 101 on Friday in a Tokyo hospital, the Imperial Household Agency said.
She had been hospitalised since March after suffering a stroke and pneumonia and had been recuperating there following treatment in intensive care.
Born Yuriko Takagi to an aristocratic family on June 4, 1923, the princess was 18 when she married the younger brother of wartime emperor Hirohito.
The couple had five children - two girls and three boys. She gave birth to her first, a daughter, in 1944 during World War II.
The imperial couple’s house burned down in an air raid and she was forced to stay in a shelter with her baby, according to Japan’s Asahi Shimbun daily.
Hirohito, who served as Japan’s commander-in-chief during its brutal march across Asia in the 1930s and 40s, surrendered in an August 1945 speech, after the United States dropped atomic bombs on Hiroshima and Nagasaki.