"I want to continue to spend enjoyable and calm days," says the 100-year-old Prince, who likes Sumo wrestling and takes half an hour every day to exercise with his wife.

Queen Elizabeth will turn 90 in April, but in the meantime there’s another royal celebrating a major milestone birthday!

Prince Mikasa, the uncle of the current Emperor Akihito of Japan, turns 100 years old today.

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Mikasa is the first member of the nation’s imperial family on record to become a centenarian, and remains the oldest surviving member of Japan’s Imperial family according to Imperial Household Agency officials.

Prince Mikasa is also believed to be the oldest living royal in the world – although the all-time longevity record is still held by Britain’s Queen Elizabeth, the Queen Mother, who died in 2002 aged 101. And longevity runs in the family as the reigning Queen Elizabeth turns 90 next year.

“Nothing will change just because I turn 100 years old,” the prince said in a statement issued through the Imperial Household Agency, which handles public affairs on the royal household’s behalf.

“While praying for the happiness of people around the world and expressing gratitude to my wife, Yuriko, who has supported me for more than 70 years, I want to continue to spend enjoyable and calm days,” Mikasa said.

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The prince has been in good health after recovering from heart surgery in 2012, an agency official is quoted as saying to The South China Morning Post.

Although his age excuses him from official duties, Prince Mikasa usually enjoys an outing every week near his residence on the Akasaka Estate, according to the Japanese newspaper Asahi Shimbun.

Last May, he watched a rehearsal of an ancient equestrian art show at the Imperial Palace and waived cheerfully to spectators.

In October, in his capacity as honorary president, he attended a gathering of the Japan’s Middle Eastern Culture Center for an early celebration of his 100th birthday.

Mikasa blew out the candles on his birthday cake, according to agency officials.

At home, the prince enjoys watching Sumo wrestling on TV, and exercises with his wife for 30 minutes every day. Mikasa and Yuriko, 92, use one-kilogram dumbbells during the daily regimen, according to agency officials.

As well as having lived through the reign of three different emperors, the prince is the only surviving member of Japan’s Imperial family to have served in the military during World War II.

After graduating from military college, the prince, an officer in the Imperial Japanese Army, was posted to Nanjing, China, under a pseudonym for a one-year tour of duty in 1943.

In a book published after the end of the war, he expressed a sense of guilt over his inability to fully grasp the criminality of Japan’s war atrocities.

Prince Mikasa and Princess Yuriko had three sons and two daughters. All three sons have predeceased him, but the couple has nine grandchildren, four of whom are official members of the imperial family, and four great-grandchildren.