You’re correct in that the narrative of Mao and communist guerrillas fighting both the Japanese and Nationalist Army is a very common one in China. However, wit

You’re correct in that the narrative of Mao and communist guerrillas fighting both the Japanese and Nationalist Army is a very common one in China. However, with the exception of the Hundred Regiments Offensive, the communist armies never engaged in the kind of the regular, brutal combat that occurred near China’s major cities against the Japanese. For political reasons, namely to portray the Nationalists as an ineffective and corrupt government, until the last decade there were few Chinese TV series or movies that depicted Nationalist armies effectively fighting the Japanese. When you look at Nationalist efforts to secure the critical Burma Road into Burma and India, and the hundreds of thousands of casualties involved in fighting rearguard actions as civilians and governments fled inland, the casualty counts are not even close. Nationalist military fatalities are generally estimated by historians to outnumber Communist military fatalities by nearly an order of magnitude. One of the reasons I wrote that WW2 set up the communists for a clean victory in the resumption of the civil war is that Japanese surrender left vast swaths of China under communist control, simply because there was not a nationalist presence in many of those areas. Hundreds of thousands of firearms, rounds of ammunition, and artillery pieces were surrendered by the Japanese to communist armies. As a result, the Communists were for the first time able to equip a large regular army, as opposed to fighting irregular war as guerrillas. I highly recommend reading Forgotten Ally by Rana Mitter. This is maybe the best popular history of China in WW2. P.s. I say this as the descendant of soldiers who fought on both sides of the civil war.