The Diet enacted a special single-use law Friday that will allow Emperor Akihito, 83, to abdicate due to his advanced age, paving the way for Crown Prince Naruhito, 57, to rise to the Imperial throne.
His abdication, which is expected to take place at the end of 2018, would be Japan's first in about 200 years, since current law only allows Imperial succession to take place when an emperor dies.
The government will decide on the timing by issuing an ordinance.