Yes, Japan was sick no doubt and exploited many. During the same period, the U.S. had Jim Crow and slaughtered many blacks, Mexicans, and Asians before. The army in Australia rounded up 1,000 of Chinese and tortured and executed them. The British and U.S. poisoned China for 200 years with Opium. The Spanish and U.S. enslaved the Philipines, men were force to work, women were sold as sex slaves.
After the liberation of Taiwan and Korea by Japan, Koreans and Taiwanese were allowed to have last names, and the feudal caste system abolished. Japan built from scratch, the education system, universities, public health system, electric grid, railway system, telecommunications system, fresh water, dams, bridges, sewers, roads, etc. that are still in use today across Taiwan and Korea.