Watch Spirit Warriors (2000) Official Trailer

I believe.

In this eerie thriller from the Philippines, a group of high schoolers finds themselves contending with more than the usual teen angst issues. It seems they've run afoul of Ulanaya, a menacing, shape-shifting ghost bent on creating terror and pandemonium throughout the land. Can these adolescent, amateur ghost hunters summon the mettle to square off against -- and vanquish -- such a formidable otherworldly nemesis?