ICN to PVG to HND

I'm visiting Korea and Japan and figure I'd add Shanghai to the mix. From the sounds of it, if I have a trip from ICN to PVG, I can stay 144 hours, and then fly from PVG to HND. This is essentially a "multi-city" itinerary but it sounds like they'll treat it as a transit. All flights are non-stop. Just want to confirm I won't need a visa / can stay for free