Here's a news report from forbes last January 14, 2017. I thinkboth will win. Both will have greater access to the PH's
(a) big, young population as consumers or needed migrant labor,
(b) SE Asia's fastest growing big economy since about 2009,
(c) nice tropical tourism destination for their people,
(d) both have quarrel over a small island that's obviously closer to Japan than China, so both have issues over international rule of law,
(e) both have ageing population, so both would need an infusion of young migrant labor from the PH, today or tomorrow.
While many support the state-sponsored population control (aka RH law to prevent "unwanted pregnancies" that become "unwanted babies" that become "unwanted workers" and entrepreneurs someday?), the Japs, Europeans, etc. envy the PH's big, young population. https://www.bloomberg.com/.../japan-turns-to-asia-s...
(f) Both have huge, big governments that are heavily indebted (220%+ of GDP for Japan, 40%+ for China but if the debt of their state corporations and banks, local governments, private corporations are included, about 240% of GDP). So both will need the money of middle class and rich Filipino tourists who can afford to travel to more countries around the world.