Japanese emperor's heart bypass operation a success

The latest surgery could prompt the royal agency to further limit the emperor's activities.

"Considering the fact that the emperor will not be getting any younger, we will continue to review the amount of duties he performs," said Ichiro Kanazawa, the Imperial Household Agency's medical supervisor.

Save for rare occasions, the Japanese imperial family is spared the intense public attention or media scrutiny that Britain's royals get.

But it serves as a comforting link with tradition at times of distress.

Five days after a devastating earthquake and tsunami struck northeastern Japan on March 11, Akihito made a rare public televised address and in April travelled to the disaster area with Empress Michiko.

Akihito's hospital stay last year gave Japan a rare opportunity to see his heir Crown Prince Naruhito, 51, step in for his father and perform public duties.

While Akihito's reign was defined by his reconciliation efforts, it is less clear what role the scholarly Naruhito may play, though royal commentators expect him to continue his father's efforts to reach out to ordinary citizens.

(Additional reporting by Elaine Lies, Kiyoshi Takenaka and Linda Sieg; Editing by Robert Birsel)