Japan joining Spain in the Spanish-American War

How would the Spanish-American War change if Japan intervened for Spain?

It could prolong and complicate the war, but Japan would likely need the Philippines as the price of intervention and Spain would still be under severe pressure.

The answer rejects a simple assertion that Japan would join Spain, stressing that states need a strategic reason to enter a war. A prior transfer of the Philippines in exchange for an alliance supplies that motive and could put a much more capable Japanese squadron in Manila Bay when the Americans arrive. Spain could then concentrate more of its limited strength on Cuba and the Caribbean, territories the speakers regard as economically more useful than the costly Philippines. Japan's fleet in 1898 was still weaker than the force that fought Russia in 1904-05, so intervention complicates and prolongs the war without guaranteeing a Spanish victory.