While I was rummaging around I also found these
That's a massive undercount of Chinese casualties. Most estimates range between 14-20million to as many as 30-40 million, depending on how you figure things.
Of course, the problem with counting Chinese WWII casualties is just how messy things were in China before, during, and after the war. In the lead up, you had decades of insanely factional and fractious civil wars (The Warlord Era), that eventually led to the rise of the Communists, the KMT, and a large faction led by Wang Jingwei. When the Japanese invaded in 1937 (realistically the start of WWII for the Chinese), Wang Jingwei ended up siding with the Japanese, Stalin ended up backing the KMT
against the communists (because Stalin saw them as stronger, and a better adversary to the Japanese - who were the bigger threat to Russia in the east), and the West backing both the KMT and the Communists against the Japanese, even though the KMT and Maoists were spending as much time fighting each other and the Jingwei faction as they spent fighting the Japanese.
Then, after the war, it wasn't in anyone's interests to talk about Chinese casualties. The Jingwei faction had been wiped out, along with the Japanese, but that was Chinese on Chinese civil warfare as usual (for the time), Mao's forces had been inept/ineffective/inactive, or accidentaly helping the Japanese by fighting against the KMT, the KMT was trying to consolidate power and didn't want to talk about killing more Chinese than Japanese, and both Stalin and the Western powers were holding their hands behind their backs and whistling at the sky like they'd had nothing to do with any of it.
By the time Mao's communists came out on top in 1949, the only thing for certain was that "there was more dead Chinese than anyone could reasonably count," and Mao had learned a valuable lesson - trust no one.