During Iwa Jima and other island attacks, when the Japanese started using kamakazi pilots, the US realized that the Japanese were not going to surrender. They had no problem throwing ten or even a hundred men at one guy in attempt of killing him. Also, the japanese government scared it's people with tales of the horror GIs would do to them, so many times there were mass suicides by jumping off cliffs and tossing babies off cliffs.
Yes, our troops were good, but you don't have to be good when your opposition consists of half starved middle aged men charging you with bamboo spears. Yes, the japanese gathered up the average male citizen and had them train with sharpened bamboo to repell invaders.
Lets just take your figure of Japanese Deaths, and call that 'Japanese Soldiers Killed' which is a reasonable figure for that. You can take a tenfold increase of that number for citizen defenders. Match that citizen defender total up with an equal number of people who will commit sucidie, kill their children, or starve while in hiding etc.
I'd estimate it closer to 2 million dead japanese and 100,000 dead American GI, vs 200,000 dead in the bombings.