President Rodrigo Duterte has vowed to "limit his mouth" when he meets with Emperor Akihito and Empress Michiko during his visit to Japan.

In a press conference at the Davao airport before he left for Tokyo Sunday night, the Chief Executive said he also looks forward to meeting Japanese Prime Minister Shinzo Abe where he would discuss security issues, particularly the situation in the Korean Peninsula, socio-economic development, peace and progress in Mindanao, build-up of modern infrastructure in the Philippines, advancement of rule of law, and tariff of Manila's exports to Tokyo.

"I therefore look forward to meeting once again Prime Minister Shinzo Abe, who I consider to be a true friend to the Philippines," he said.

Duterte said he would also have an audience with the Emperor.

He said he will take the occasion to personally convey gratitude for Japan's friendship with the Philippines, "which has grown stronger under His Majesty's reign."

Duterte, who is known for his foul mouth, said, "I supposed I have to limit my mouth there, except may be to bring warm greetings of the Filipino nation, a grateful nation to Japan, as a matter of fact."

He also said his audience with the Emperor was "kind of a homage" to him before he abdicates.

The President recalled that he failed to meet with the Emperor during his first visit to Japan last year because the uncle of the Emperor passed away.

Meanwhile, Duterte said he does not doubt that Japan would help his government in rebuilding the war-torn Marawi City.

"I think the damage alone and the dimension of the distraction would tell Japan that we need their very best assistance. I do not doubt that Japan can graciously give us help. Of course, we do not expect Japan to solve all the problems for us, but I would see significant assistance considering, as I said, the dimension of the distraction. I am hopeful that we can improve on these things periodically because we need to rehabilitate Marawi," he said.

He warned that failure to rebuild the city could "have grave consequences for Mindanao and for the entire country."

After about five months of fighting, Duterte declared Marawi free from Islamic State-inspired Maute terrorists recently.

Duterte also said he has to discuss with Abe the issue on the Korean Peninsula, particularly "how to deal with this problem if it gets worse."

He said nuclear war is totally unacceptable, stressing that somebody has to talk with North Korean leader Kim Jong-un, "to convince him to sit down in a round table." Celerina Monte/DMS