Japanese Emperor Akihito and Empress Michiko visited Okinawa on Tuesday to pay tribute to the war dead, with their trip to the major battlefield of World War II possibly their last before the emperor's abdication in April next year.

During the three-day trip to the southern island prefecture, the 11th for the imperial couple, they will stay in Naha and travel for the first time to Japan's westernmost island of Yonaguni, from where Taiwan can be seen.

The trip was arranged following a strong desire expressed by the emperor and empress who have long felt sympathy for Okinawa, where around a quarter of the residents died in a three-month ground battle in 1945. Okinawa was occupied by the United States after the war until its reversion to Japan in 1972.

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After arriving in Okinawa, the two will visit the National War Dead Peace Mausoleum in the city of Itoman on the main island to commemorate the war dead. They will make a daytrip the next day to Yonaguni Island to visit a stone monument marking Japan's westernmost point.

On the final day, the imperial couple will travel to the city of Tomigusuku on the main island to visit Okinawa Karate Kaikan, a facility dedicated to the karate martial art, which is said to have its roots in Okinawa, before flying back to Tokyo.

The imperial couple last visited Okinawa in June 2014 ahead of the 70th anniversary of the end of the war in 1945.

As crown prince and crown princess, they first visited Okinawa in 1975, at a time when attitudes to the imperial family among local residents were complicated due to the war, which was fought under the name of Emperor Akihito's father, Emperor Hirohito.

After ascending to the throne in 1989, the emperor became the first Japanese monarch to visit the prefecture in 1993.

The couple offers a silent prayer every year on four war-related dates -- June 23, when the Battle of Okinawa ended, Aug. 6, when the first U.S. atomic bomb was detonated over Hiroshima, Aug. 9, the day of the atomic bombing of Nagasaki, and Aug. 15, when Emperor Hirohito told the nation over the radio of the end of the war.

The couple considers them as "four days that should never be forgotten." Emperor Hirohito, posthumously known as Emperor Showa, was commander in chief of the Japanese military before and during the war.

The 84-year-old emperor is set to retire on April 30, 2019, having signaled his wish to step down due to concern about his advanced age and weakening health. His elder son Crown Prince Naruhito, 58, will succeed to the Chrysanthemum Throne on the following day.