I personally have never noticed any left luggage provisions in either the international or domestic terminals, however I have been advised that there is a facility for storing your luggage.
From my understanding they are not secured lockers, your luggage will be left on shelves which are unsecured, so you may want to ensure you have locks for your luggage. You will need to ask for the Left Luggage Office once you arrive.
Another option is to leave any excess luggage at the hotel you are staying at in Manila, this to me would be a safer option of the two in the absence of secure lockers......Brett
