▁by ▁large - scale ▁imm igration ▁of ▁Japanese ▁to ▁the ▁Philippines , ▁mainly ▁mer ch ants , ▁garden ers ▁and ▁prost it utes ▁(' kar ay uki - san '). ▁D ava o ▁that ▁time ▁had ▁over ▁ 2 0 , 0 0 0 ▁eth nic ▁Japanese ▁residents . ▁By ▁ 1 9 3 5 , ▁it ▁was ▁estimated ▁that ▁Japanese ▁imm igr ants ▁domin ated ▁ 3 5 % ▁of ▁Philipp ine ▁ret ail ▁trade . ▁In vest ments ▁included ▁extensive ▁agricult ural ▁hold ings ▁and ▁natural ▁resource ▁development . ▁By ▁ 1 9 4 0 , ▁some ▁ 4 0 % ▁of ▁Philipp ine ▁exports ▁to ▁Japan ▁were ▁iron , ▁co pper , ▁mang an ese ▁and ▁chrome . ▁ ▁During ▁World ▁War ▁II , ▁immediately ▁after ▁the ▁attack ▁on ▁Pear l ▁Har bor , ▁Japanese ▁forces ▁inv aded ▁and ▁quickly ▁over c ame ▁resistance ▁by ▁the ▁United ▁States ▁and ▁Philipp ine ▁Commonwealth ▁military . ▁Str ateg ically , ▁Japan ▁needed ▁the ▁Philippines ▁to ▁prevent ▁its ▁use ▁by ▁Al lied ▁forces ▁as ▁a ▁forward ▁base ▁of ▁operations ▁against ▁the ▁Japanese ▁home ▁islands , ▁and ▁against ▁its ▁plans ▁for ▁the ▁further ▁con quest ▁of ▁S out heast ▁Asia . ▁In ▁ 1 9 4 3 , ▁a ▁pu ppet ▁government , ▁the ▁Second ▁Philipp ine ▁Republic , ▁was ▁established , ▁but ▁gained ▁little ▁popular ▁support , ▁primarily ▁due ▁to ▁the ▁Imperial ▁Japanese ▁Army ' s ▁brut al ▁conduct ▁towards ▁the ▁Philipp ine ▁civil ian ▁population . ▁During ▁the ▁course ▁of ▁the ▁Japanese