What did the Japanese get in return? In return the Americans recognized that Imperial Japan could take over Korea.
fulltimestudent, thanks for posting that - certainly a fact that is otherwise kept very quiet!
The whole business could be placed under the heading of "Great Power Politics" - something that is certainly not unique to the Korean Peninsula. In other places - such as Western Papua - the victims get ignored and the matter quietly forgotten about. For a variety of reasons, though, not the case with Korea; where it periodically comes back to bite the participants on the backside!