China can win but only through counter-attack, you can’t beat Japan by blocking thier path with units on defence.
Instead, let them take ground for FREE during thier move, and then counter thier infantry 1 at a time through counter-attacks. This severely limits the amount of troops japan can keep on the ground, and in turn, restricts the amount of aircraft they can use to support them (Because Japan is not likely to suicide fgts and tac bmb’s into plain chinese infantry)
This has been an effective method, each time I’ve used it. It helps the allied effort, by forcing japan to commit more and more troops.
In short - Play hide and seek with Japanese Aircraft.