24hour visa exemption

I am an Indian studying in Japan. I will be travelling to Kolkata, India and back. The flight is from Osaka-Kunming-Kolkata. But the flight to Kunming from Osaka has a stopover(technical may be) at Shanghai. Though my entire journey is within 24 hours but do i need to clear immigration at Shanghai though my flight is destined to Kunming and not Shanghai. Will kunming be considered as first port of entry or will Shanghai be considered?Similarly when i come back to Osaka from Kolkata. The flight says Kolkata-Kunming-Osaka with a stopover at Shanghai of 1 hr 20 mins while coming from Kunming to Osaka. Will stopover at Shanghai be considered as last port of departure or will Kunming be considered so?