As Philippine President Rodrigo Duterte prepares to make his first visit to Japan since taking office in June, Tokyo is looking to play peacemaker between Washington and Manila as the tough-talking leader threatens to change the geopolitical calculus in the South China Sea.

During his three-day visit starting Tuesday, Duterte is likely to seek economic assistance and investment from Japan to shore up the Philippines' battered economy, concessions Japan is nearly always ready to offer.

"We would like to further enhance our strategic partnership with the Philippines," Chief Cabinet Secretary Yoshihide Suga told reporters on Friday.