Japanese Emperor Naruhito met Indonesian President Joko Widodo on Monday during his first state trip since ascending the Chrysanthemum Throne in 2019.
Naruhito and Empress Masako's June 17-23 visit to Southeast Asia's biggest economy came after Widodo invited the emperor during a trip to Tokyo last year.
The royal couple arrived at a presidential palace south of the capital Jakarta, flanked by dozens of well-wishers shouting "Welcome to Indonesia!" and a marching band that played the Japanese national anthem.
"The visit of the Emperor and Empress to Indonesia has further strengthened the friendship between our people," Widodo told reporters before a formal lunch meeting.
"Such a solid foundation is necessary for the development of a strategic partnership between our two countries, especially in the economic field."
Widodo and first lady Iriana, who like many Indonesians goes by one name, walked with the royal couple around the palace gardens and held a tree-planting welcome ceremony.
Tokyo and Jakarta have moved to boost ties in recent years, with Japanese officials citing the importance of Indonesia's emerging economy and its strategic location close to global shipping lanes.
Japan ruled Indonesia from 1942 for more than three years. Tokyo's surrender in World War II was followed by an armed uprising against Dutch rule and Indonesia's independence.
On Tuesday, the royal couple will visit a military cemetery in Jakarta where 28 former Japanese soldiers who stayed and fought in the Indonesian War of Independence (1945-1949) are buried.
They will also pay a visit to a new mass rapid transit (MRT) train depot in Jakarta that was built with Japanese help and a Tokyo-funded pumping station that prevents flooding.
Naruhito is also scheduled to visit the central Javan city of Yogyakarta to meet the provincial monarch, and will also go to Borobudur, the world's largest Buddhist temple.
The Japanese royal couple have gradually resumed public duties after limiting them during the Covid-19 pandemic.
Last year, they made their first trip abroad since the enthronement to attend Queen Elizabeth II's funeral in London.
Previous Japanese monarchs visited Indonesia in 1962 and 1991.