Japan's Crown Prince Naruhito and Crown Princess Masako attended the coronation of the new Dutch king on Tuesday at a historic church with members of other royal families.
Prince Willem-Alexander became the Netherlands' first king in more than a century after his mother Queen Beatrix abdicated following 33 years on the throne.
In attending the ceremony, the 49-year-old Japanese crown princess, who has been struggling with a stress-induced illness for a long time, made her first official overseas trip in 11 years.
In addition to government officials and key parliamentary figures, members of royal families from about 20 countries across Europe, the Middle East, Asia and elsewhere were among those attending the ceremony at the Nieuwe Kerk, a Protestant church which has been the site for Dutch royal inaugurations.
Japanese Ambassador to the Netherlands Yasumasa Nagamine, who also attended the ceremony, told a press conference that the Japanese crown prince and princess had seats in the front row and exchanged words with royal family members.
After the new Dutch king took his vows at the Nieuwe Kerk, the royal families from across the globe posed for photos and then moved to the Royal Palace nearby for a reception.
In Tokyo, Japan's Imperial Household Agency said Emperor Akihito has sent a congratulatory telegram to the new Dutch king.
Following the coronation and reception, Crown Prince Naruhito took part in a celebratory parade at IJ lake, while his wife skipped the event as scheduled to reduce her workload and returned to their hotel to rest.
He then attended a dinner banquet hosted by the Dutch king and his wife at a music hall.
The crown prince and princess are scheduled to leave the Netherlands on May 2 and return to Japan the following day.