It was his first birthday since he announced in August that his advancing age and weakening health mean he may no longer be able to carry out his duties, setting the stage for Japan to prepare for an historic abdication.
The Imperial Palace said some 33,300 people -- the biggest crowd since Akihito ascended to the throne in 1989 -- attended his birthday address, waving small Japanese flags as crowds shouted "Banzai" or "Long live".
"If this is going to be his last time, I'm glad I got to see him," said Reiko Takahashi.
Also attending the emperor's address, Takako Miyazaki expressed the view of many Japanese.
"The emperor is quite old and if he says he wants to abdicate I think he should be allowed to," she said.
Flanked by Empress Michiko and other members of the royal household, the soft-spoken monarch greeted well-wishers from a glass-covered balcony at the palace, surrounded by stone walls and mossy moats.
"I wish you all health and happiness, and I pray the next year will be cheerful and peaceful," the emperor said in his address.
Ahead of his birthday, Akihito thanked the country for considering his message indicating his desire to abdicate, telling reporters: "I am profoundly grateful that many people have lent an ear to my words and are giving sincere thought to the matter in their respective positions."
