Akihito's son, Crown Prince Naruhito, will ascend the Chrysanthemum throne.
The abdication is likely to take place at the end of 2018, which would mark three decades on the Chrysanthemum throne for Akihito.
It would be an unprecedented move in modern Japan.
At the height of the crisis, the Emperor and Empress opened their hospital to those in need of medical emergency. They also opened their hot bath facilities in their summer palace to a nearby shelter.
Only those of us who served in Japan in the 1950s might have shaken our heads after Thursday's frontpage photos in the New York Times that showed Emperor Akihito and Empress Michiko consoling evacuees.