Will I be needing transit visa for China? I do not plan to step out of the airport.

I am travelling by China Eastern from CCU (Kolkata) to NRT (Tokyo). The flight makes first stop at KMG (Kunming) for 2 hr 15 mins and another at PVG (Sanghai) for 6 hrs 35 mins before proceedings towards Tokyo. I am an Indian citizen with passport valid for more than 3 years.