Earlier this week, Emperor Akihito of Japan addressed the nation in a televised address for only the second time in his 27-year reign. The 82-year-old monarch, who has undergone heart surgery and cancer treatment, said that he fears his declining health may make it difficult for him to continue with his duties as emperor “with my whole being as I have done until now.” The speech was widely seen as a plea to the Japanese Parliament to change the country’s existing laws, which mandate that the emperor serve until his death, in order to allow Akihito to abdicate in favor of his son. Polls have shown more than 85 percent of Japanese people believe Parliament should honor the emperor’s desire to step down. As Prime Minister Shinzo Abe and the rest of the government decide how to proceed, here are some things you might not know about Emperor Akihito and Japan’s enduring imperial dynasty.

Japan is the oldest continuous monarchy in the world.

Though it’s a liberal democracy, Japan is also the oldest continuous monarchy in the world. According to widely accepted (though somewhat legendary) genealogy, Akihito’s family has ruled for some 2,700 years. Though we know little of the first 25 emperors—starting in 600 B.C. with Emperor Jimmu, said to be descended from the sun goddess Amaterasu—there is solid evidence of an unbroken hereditary line stretching from 500 A.D. to today.

The monarchy is often referred to as the Chrysanthemum Throne, which is a metaphor—but also an actual thing.

The kiku (which is Japanese for chrysanthemum) was originally introduced to Japan from China. As legend has it, the flower came from a town where people lived to be more than 100 years old, all thanks to drinking water from a mountain spring surrounded by chrysanthemums. Japanese passports bear a seal of the flower, now an all-important symbol of the nation itself. The Imperial Palace in Tokyo, where Akihito and his family live, contains an ornate chair known as the Takamikura—an actual chrysanthemum throne used for coronation ceremonies.

Japan even bases its calendar on the emperor.

Japan has a unique calendar system that defines the year according to the emperor’s reign. For example, 2016 is expressed as Akihito’s 28th year on the throne. When his successor is crowned, the date on the calendar will reset to Year One. According to modern Japanese custom, when emperors die they receive new names reflecting the era in which they ruled. Akihito’s father, Hirohito, who ruled Japan during World War II, is known posthumously as Showa (“radiant Japan”). Akihito, crowned in 1989, will become Heisei, or “peace everywhere.”

Akihito broke with tradition when he married, becoming the first Japanese monarch to marry a commoner.

Until the 20th century, emperors usually had a chief wife and several concubines (all from noble families). Akihito was the first emperor to have permission to marry a commoner, and he did so, falling in love with Michiko Shoda (now Empress Nagako) after meeting her on a tennis court. They married in 1959, and went on to have three children. Akihito’s elder son, Crown Prince Naruhito, also married a commoner, the former diplomat Masako Owada.

Emperor Akihito's Video Message. (Credit: Tomohiro Ohsumi / Getty Images)
Emperor Akihito’s Video Message. (Credit: Tomohiro Ohsumi / Getty Images)

This week’s address was only the second time in Akihito’s reign—and the third time in history—that the emperor has addressed the Japanese public via radio or TV.

In 2011, Japanese TV networks broadcast the first public address from Akihito, who sought to soothe the nation after a devastating earthquake-tsunami hit the northeast coast of Japan, triggering a disaster at the nuclear power plant in Fukushima. With 20,000 people dead or missing and tens of thousands displaced by these events, Emperor Akihito and Empress Nagako later visited the disaster zone and met with evacuees. Akihito’s address evoked memories of his father’s unprecedented radio broadcast to the nation in August 1945, when he announced Japan’s defeat by the Allies in World War II. For many Japanese, Hirohito’s speech was the first time they had heard the emperor’s voice.

Akihito would be the first Japanese monarch in 200 years to step down.

It didn’t use to be such a big deal for the emperor to abdicate the throne; more than half of Japan’s monarchs throughout history have done so. The last one was Emperor Kokaku, who stepped down in 1817. Japan’s emperor was long known as tenno, or “heavenly sovereign,” with a divine right to rule. But with the rise of the cult of emperor worship in the 19th century—fully encouraged by Japan’s political leaders—the emperor effectively became a demigod, and stepping down became an unthinkable step. As part of Japan’s surrender in World War II, Hirohito actually had to publicly renounce “the false conception that the emperor is divine.” Though Japan’s 1947 constitution effectively reduced the emperor to a figurehead, the office still has considerable power as a “symbol of the state and the unity of the people.”

With only one male heir in the next generation of the royal family, Japan has considered amending the law to allow a woman to inherit the throne.

Though historically, women could ascend to the Japanese throne and rule in their own right—eight of Japan’s rulers have been women—Japan’s Imperial Household Law now mandates that only male heirs can inherit the throne. Though there had been talk of changing the law to include female members of the royal family in the imperial succession as late as 2005, any plans to do so were dropped after Princess Kiko (wife of Akihito’s younger son, Prince Akishino) gave birth to a son the following year. Still, as Prince Hisahito is the only male born into Japan’s royal family since 1965, Akihito’s possible retirement could revive talk of amending the law in order to include Princess Aiko (daughter of Crown Prince Naruhito and Princess Masako) as well as Hisahito’s two sisters in the line of succession.