Emperor Akihito and Empress Michiko on Friday hosted their last garden party before an imperial succession next year, enjoying exchanges with distinguished guests.

The event is held in spring and autumn at Tokyo's Akasaka Imperial Gardens. As the imperial family will be busy with ceremonies before and after Emperor Akihito's planned abdication in April, garden parties are unlikely to take place in either season next year.

Signaling the significance of the event, Crown Princess Masako, who has long been battling a stress-induced illness, stayed until the end of the event on Friday for the first time in 15 years. In recent years, she had left the biannual party early.

In the rain, the imperial couple exchanged greetings and mingled with guests who have made notable achievements in the worlds of culture, sports and science.

Among those who were invited were astronaut Norishige Kanai, playwright Koki Mitani, Ryuta Ibaragi, the governor of Okayama Prefecture, hit hard by deadly torrential rains in July, and Momoka Muraoka, an alpine sit skier who won a gold medal at Pyeongchang Winter Paralympics.

The emperor and empress will not perform any official duties after their eldest son, Crown Prince Naruhito, ascends the imperial throne on May 1, 2019, the day after his 84-year-old father steps down based on his desire to do so due to his advanced age and failing health.

In the last few years, Crown Princess Masako has engaged in more official duties and shown signs of a solid recovery.