Emperor Akihito will step down on April 30, marking the first Japanese monarch to abdicate the throne in about 200 years.

The 85-year-old emperor, Japan's 125th according to the traditional order of succession, expressed his desire to step down in a rare video message broadcast in 2016.

During the video message he expressed his concern that owing to his age he might not be able to fulfill his official duties.

A year later, the parliament passed a one-off bill enabling Emperor Akihito to step down.

The government ordinance on the new era name will be promulgated as early as Monday afternoon following its signing by Emperor Akihito.