I would put the Kempeitai, Unit 731 and most of the guards working the POW's along the Burma–Siam Railway up beside the Einsatzkommandos when it comes to brutality.
“Government has three primary functions. It should provide for military defense of the nation. It should enforce contracts between individuals. It should protect citizens from crimes against themselves or their property. When government-- in pursuit of good intentions tries to rearrange the economy, legislate morality, or help special interests, the cost come in inefficiency, lack of motivation, and loss of freedom. Government should be a referee, not an active player.” - Milton Friedman