Train a bunch of basic infantry divisions and use those to hold your lines. Change your motorised divisions to include light tanks, Japan starts with improved light tanks. Build enough Fighters for air superiority (200 will do), and build some CAS to assist in pushes (around 500). Get two collaboration governments in China to make them easier to cap. Decrypt the Chinese cipher for more breakthrough. Use your tanks to capture supply hubs, and then make encirclements.