Tokyo, Oct 28 (IANS): Prince Mikasa, the 100-year-old uncle of Japanese Emperor Akihito, has died of heart failure, a media reported.

The youngest brother of the late Emperor Showa, Prince Mikasa was the oldest Imperial family member since the Meiji era. He breathed his last at 8.34 a.m. at St. Luke's International Hospital in Tokyo, Japan News reported.

According to Hirokazu Nagawa, the medical supervisor of the Imperial Household, said the Prince's physical condition had been stable in recent days, but on Thursday his heart rate started to slow and fell into a state of cardiac arrest.

Prince Mikasa, fifth in line to the Chrysanthemum Throne, was also known as Takahito. He was born in the Tokyo royal palace on December 2, 1915. He was the youngest son of Emperor Taisho and Empress Teimei. 

On December 2 last year, Prince Mikasa turned 100 years old. 

He was the first member of the royal family to get a driver's license and was an outspoken advocate of birth control, though he conceded after his fourth child was born, "It is not easy to practice what you preach," NYT reported.

Prince Mikasa's service in a calvary regiment took him to China, including the Japanese army's headquarters in Nanking in 1943 and 1944, as a staff officer. He said he became increasingly shocked by the brutality of Japanese troops during World War II. At one point, he wrote in his best-selling memoir, he saw a film of Chinese prisoners "made to march on the plains of Manchuria for poison gas experiments on humans," the Washington Post reported.

Prime Minister Shinzo Abe expressed his "heartfelt condolences" over the passing of Prince Mikasa on Thursday.

"As a member of the Imperial family, [the prince] played important roles in a wide variety of fields, including international friendship, sports, recreation, the arts, culture, medical affairs and welfare," the Prime Minister said.

With his passing, the Imperial family now has four male members in the line of succession.