They treat them absolutely horribly. With extreme cruelty, barbarity and savagery. The men were sometimes forced to work for the Japanese as slave laborers. People are force to bow to the Japanese soldiers or they will be beaten, some were killed because of not bowing. Children and womens are asked to stay at home. if they captured by the japanese, they might be raped and then killed, or forced to be "comfort women" (prostitutes) for the Japanese Army, in Army-operated brothels. At least they were not murdered immediately. Everybody else in Asia despises the Japanese to this day, not just for what they did, but for the fact that they won't admit it, and see nothing wrong in what they did. See the "Rape of Nanking", where Japanese troops were allowed free rein for six weeks after capturing that Chinese city. 300,000 Chinese civilians died in those next six weeks in Nanking..
They also used them to get info or as ransom. basically you didn't want to be a prisoner of theirs. most of the lower soldiers were following orders but they still brutal and hardly any apologized for what they did. http://wiki.answers.com/Q/How_did_the_Japanese_treat_the_people_they_conquered