Japan's government has approved a one-off bill which, if passed, will allow Emperor Akihito to abdicate.
The 83-year-old emperor
that his age and health were making it hard for him to fulfil his official duties.
But there is no provision under existing law for him to abdicate and be succeeded by Crown Prince Naruhito.
The bill will now pass to the parliament, where it is widely expected to be passed.
Akihito, who has had heart surgery and was treated for prostate cancer, has been on the throne in Japan since the death of his father, Hirohito, in 1989.
The emperor is constitutionally barred from making any comments on politics, so he could not say explicitly that he wanted to stand down.
But in a rare address to the nation in August, he said he was beginning to feel "various constraints such as in my physical fitness" which caused him to "contemplate on my role and my duties as the Emperor in the days to come".
The government has said they will take his wishes seriously and reconsider the abdication laws.
Akihito's eldest son, 56-year-old Crown Prince Naruhito, is first in line to the Chrysanthemum Throne, followed by his younger brother, Prince Akishino.
Women are not allowed to inherit the throne and so Princess Aiko, the daughter of Crown Prince Naruhito, cannot succeed her father.