Separate tickets from different airline-transiting in PVG

Hi, I am a Sri Lankan citizen and bear a Sri Lankan Passport. I am working in Japan and travelling back to Sri Lanka.

My question is, if I reserve airline tickets from different airlines (Tokyo to PVG on China Eastern and PVG to Colombo on Sri Lankan airlines) with a maximum layover of 18 hours, do I still need visa?. (Two different tickets since I am ordering them separately)

As per my understanding, I will need to walk out of the immigration and collect my bags and again check in with the new airlines since it was different from the earlier.