Crown Prince Akishino and his wife, Crown Princess Kiko, left Japan on Thursday for a tour of Poland and Finland where they will join in celebrations marking the centenary of Japan establishing ties with the two European countries.
The couple's tour is the first overseas trip by members of the imperial family since the May 1 ascension of Emperor Naruhito, the elder brother of the crown prince. It is also the couple's first official visit to the two countries.
During his time as crown prince, Emperor Naruhito used a government jet for overseas visits, but Crown Prince Akishino, who is now first in line to the throne, will fly on a commercial plane.
The Imperial Household Agency said he has not had any issues when flying on commercial airlines in the past.
The couple is expected to arrive in the Polish capital, Warsaw, on Thursday evening, after transferring in Frankfurt. They will make a courtesy call to Polish President Andrzej Duda, attend ceremonies and visit the city of Krakow during their stay.
They will move on to the Finnish capital, Helsinki, next Tuesday, and meet Finnish President Sauli Niinisto the following day.
During their visit to the Nordic country, the couple will visit a so-called neuvola facility, part of the Finnish child care system of the same name that has been garnering increased attention in Japan amid the country's low birthrate.
They will return to Japan on the morning of July 6, arriving at Narita airport in Chiba Prefecture.