King Carl XVI Gustaf of Sweden said Tuesday he hopes to maintain friendly relations with Emperor Akihito after he abdicates in April next year, the first Japanese monarch to relinquish the throne in more than 200 years.

"We have agreed to have...very good communication...in many different occasions both here and elsewhere" in the future, the king said in a press conference, a day after he and Queen Silvia had dinner with Emperor Akihito and Empress Michiko.

In response to a question about his views on the emperor's abdication, the king said, "This is something that the emperor has decided and this is something...Japan has now accepted."

The emperor, who has undergone heart surgery and treatment for prostate cancer, signaled his wish to retire in a rare video message in August 2016, citing concern about his advanced age and weakening health that could prevent him from fulfilling his constitutional role as the symbol of the state.

In 1980, Sweden became the first monarchy in Europe to change its succession rules so that the first-born child of the monarch is heir to the throne, regardless of gender. Other monarchies including the Netherlands and Britain followed suit.

In Japan, meanwhile, the Imperial House Law stipulates that only males born to the male lineage of the imperial family can ascend the throne, raising concern about securing stable succession with the size of the imperial family shrinking.

The Swedish king said it was "natural" that the Scandinavian country introduced the eldest-child preference.

He said his motto has always been to reign in line with "changes of the society" and with the "expectations of the Swedish population."

(The Swedish king and queen meet with Crown Prince Naruhito and Crown Princess Masako)