The government will soon start discussing how to achieve a stable Imperial succession, including the creation of female branches of the royal family.
Chief Cabinet Secretary Yoshihide Suga said during a Diet committee session Monday that the government will study whether to allow female members to remain in the Imperial family even when they marry commoners.
The process will start immediately after Crown Prince Naruhito succeeds Emperor Akihito on May 1, he said.
The Imperial House Law stipulates that only males can ascend the throne and requires women marrying outside the Imperial family to abandon their royal status.
The government has held discussions in the past on whether a female member can ascend the throne, but Prime Minister Shinzo Abe's ruling Liberal Democratic Party has been reluctant about changing the law to allow female monarchs.
Abe said in the Diet committee session, "Because this is an extremely important issue related to the foundation of the nation, we have to give careful consideration to the matter."
The Emperor, who is 85 years old, will be Japan's first living monarch in around two centuries to abdicate. The date has been set for April 30.
A one-off law was enacted in June 2017 allowing him to pass his status to his 59-year-old son after he indicated his desire to step down in a rare video message.
While the government-led process stopped short of resuming a debate on female succession, the Diet adopted a nonbinding resolution requesting that the government consider how to ensure stable succession.
There are currently 18 Imperial family members, 13 of whom are female.
After the Crown Prince ascends the Chrysanthemum Throne, there will be only three male heirs — the Crown Prince's younger brother, Prince Akishino, 53, the Emperor's only grandson, Prince Hisahito, 12, and Prince Hitachi, 83, the younger brother of the Emperor.