(CNN) -- Japan's 77-year-old emperor is currently in hospital, several days after coming down with a fever, a spokesperson with the Imperial Household Agency says.





Emperor Akihito, a ceremonial but revered figure in the Japan, was suffering from a worsening case of bronchitis and the fever he contracted Thursday, according to the spokesperson, who declined to be identified due to the agency's media protocol.





"He appears to be fatigued and has lost some resistance to fight against sickness," the spokesperson said. "To be on the safe side, he was hospitalized (Sunday night) at University of Tokyo Hospital."





It is the emperor's second time in a hospital this year, after getting medical treatment in February for extensive tests of his coronary arteries.





In recent years some analysts believe Akihito's health has been affected by stress. The issues of no male heir for Crown Prince Naruhito, the continued talk of constitutional changes for females to rule and family rifts over the role of the Imperial Household Agency were speculated to be the cause.





Tsugunomiya Akihito was born on December 23, 1933 in Tokyo to Emperor Hirohito and Empress Nagako Kuniat as their fifth child and first son.





According to Japanese legend, he is a direct descendant of Japan's first emperor Jimmu, circa 660 BC. Akihito means "shining pinnacle of virtue," and Tsugunomiya means "prince of the august succession and enlightened benevolence."





At about the age of five, Akihito was separated from his parents, in accordance with Japanese custom at the time, and raised and educated by chamberlains and tutors.





His youth was packed with events so dramatic that they today seem unimaginable, including Japan's brutal military invasion of China, its foray into World War II and subsequent defeat followed by an unprecedented foreign occupation.





Akihito's post WWII private tutor was an American Quaker, Elizabeth Gray-Vining from Philadelphia, who also happened to be the only foreign guest at his wedding. Married to Michiko Shoda in 1959, he was the first Japanese crown prince to marry a commoner (they met playing tennis), despite the fact there was a designated list of about 800 potential candidates.





The marriage produced three children; Hiro no miya Naruhito Shinno, Crown Prince Naruhito (born February 23, 1960), Akishino no miya Fumihito Shinno, Prince Akishino (born November 30, 1965), and Nori no miya Sayako Naishinno, Princess Sayako (born April 8, 1969).





On November 12, 1990, Akihito ascended to the Chrysanthemum Throne -- the oldest hereditary monarchy in the world -- as the 125th Emperor of Japan, one year and ten months after the death of Emperor Hirohito.





The position, per Japan's constitution, is defined as "the symbol of the state and of the unity of the people." That said, the office's involvement in day-to-day government affairs tends to be minimal.





Akihito broke from precedent following Japan's epic 9.0 magnitude earthquake and subsequent tsunami earlier this year, when he gave a historic, televised speech on March 16. In it, he encouraged citizens to put forth their "best effort to save all suffering people" and he applauded his countrymen's handling of the crisis.





"I truly hope the victims of the disaster never give up hope, take care of themselves, and live strong for tomorrow," he said in a calm and poignant oration delivered from the Imperial Palace. "Also, I want all citizens of Japan to remember everyone who has been affected by the devastation, not only today but for a long time afterwards -- and help with the recovery."





CNN Library contributed to this report.
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