“The government is expecting the bill to be enacted smoothly,” Chief Cabinet Secretary Yoshihide Suga said at a press conference.

The bill states the public’s “understanding” and “sympathy” for the aging emperor’s “deep concern” about becoming unable to fulfil his duties eventually as a reason to set up the special-case abdication law.

The timing of the emperor’s retirement will be set by a government ordinance after the enactment and promulgation of a special-case abdication law.

Prime Minister Shinzo Abe’s government launched the preparations of a legal revision to enable the emperor to retire following his unusual televised address to the public last August signalling his desire to step down due to his advanced age and weakening health.

Currently, only posthumous succession is allowed as the Imperial House Law, which stipulates imperial matters, lacks a provision regarding an abdication by a reigning emperor.

The government avoided creating a permanent abdication system. It instead drafted a bill for one-off abdication legislation and a supplementary provision to the Imperial House Law to enable the special-case law to serve as a precedent for future emperors.

The bill is set to be submitted to the Diet later in the day, with the government expecting its enactment by the end of the current Diet session in mid-June.

But opinions remain divided among ruling and opposition parties over how and by when the government should come up with a solution to cope with the ever-shrinking royal family.

The main opposition Democratic Party has been seeking the abdication bill to have an attached special resolution calling for deeper debate on enabling princesses to establish their own branches within the imperial family after they marry commoners.

But Abe’s ruling Liberal Democratic Party has been reluctant toward that move, with conservatives within the party wary that allowing princesses to stay in the imperial family after marriage could eventually pave the way for women to inherit the throne.

Princess Mako’s expected marriage is set to reduce the number of imperial family members, including the emperor, to 18. Currently, there are only four heirs to the throne and Prince Hisahito, 10, Princess Mako’s younger brother, is the only male member of his generation.

After Emperor Akihito relinquishes the Chrysanthemum throne, he will be called “joko,” an abbreviation of “daijo tenno”, a title that was given in the past to an abdicated emperor, according to the bill.

Empress Michiko will be given a new title, “jokogo,” which means “wife of joko” after her husband’s abdication.

Emperor Akihito’s funeral ceremony and tomb will be equivalent in status to those of past emperors, the bill said, adding The Emperor’s Birthday holiday on Dec. 23 will be changed to Feb. 23, the birthday of Crown Prince Naruhito, 57.

The timing of his abdication will be decided under an ordinance within three years after the law’s promulgation after consulting with the Imperial House Council whose members including the prime minister, a Supreme Court justice and the Imperial Household Agency’s grand steward, as well as two imperial family members, the bill said.

A series of ritual ceremonies will be held over a period of a year for the accession of the new emperor. The government is also planning to hold an abdication ceremony for the first time in around two centuries by studying ceremonial practices in the past.

After Crown Prince Naruhito ascends the throne, his younger brother Prince Akishino, 51, will be the next in line to the throne. Prince Akishino’s annual budget allocation for his private expenses will increase threefold to 91.5 million yen (US$822,000), according to the bill.

The enactment of the bill will make Emperor Akihito the first emperor to abdicate since Emperor Kokaku, who relinquished the throne in 1817. Historically, abdication of Japanese emperors was common, with about half of the 125 Japanese emperors having abdicated.