Along with China, Japan is one of Phili-tan's oldest brothers and been trading were her even before Spain claimed her as a colony. Aside from the bloody happenings of WWII, Japan's relations with her have been well. Phili-tan's national hero was even of Japanese descent.
I see Japan to be more of an older brother to Phili-tan since I have the preference with pairing Phili-tan with South Korea. ^_^
Japan Shimeji by crazy-chibi
Philippines Shimeji by xKaii-chan
Hetalia belongs to Hidekaz Himaruya