actually, 3 million chinese only referred to chinese soldiers.  look at this link provided by my bro:
 http://www.worldwar2database.com/html/frame4.htm 
notice that chinese civilian casualties was N/A, cause i think it's hard to keep track.
man Japanese has been killing chinese since 1904 russo-japanese war in manchuria.  japanese used chinese civilians to test their poison gas, disected live human and all crap since 1931 when japanese took over manchuria.  and as u know more ppl were killed when japanese launched full invasion of China from 1937-1945.   
 i heard (long time ago) that an estimation of 30 million chinese were killed in ww2?  not sure but i believe the # must be enormous.