US->Japan->China->US

I have a flight from Detroit->Tokyo on Dec 14 and then Shanghai->Detroit on Dec 31, purchased on one itinerary through Delta.

I also have a flight from Tokyo->Shanghai on Dec 28, purchased through another carrier.

My route is Detroit->Tokyo->Shanghai->Detroit, so I believe I should qualify for the 144-hour transit.

However, I'm concerned that there will be an issue or confusion when I present my itinerary to Chinese immigration, because my first flight from the US was purchased together with my final flight back to the US. My Delta receipt has both listed together. Of course, I will present the itinerary for the Tokyo->Shanghai flight, but I'm still worried this might be a mess because of how I purchased the other two flights in one transaction.

Anyone have experience with a similar scenario? Thanks.