Casualties of the 2 atomic bombs - About 200,000
http://www.atomicarchive.com/Docs/MED/med_chp10.shtml
Chinese civilians killed by the Japanese during Japan's invasions of China during WWII - About 17 million
http://www.japan-101.com/history/sino1.htm
I don't feel bad at all for Japan. They killed so many civilians. Out of those 17 million chinese they killed it says 10 million or so were collateral damage of military operations which is understanble to some extent, but the other 7 million were basically murdered in non-military operations.