Roundtrip

We fly from France to Tokio but with a overlay in Shangai of 5 hours. 1 week later we take a flight from Tokio to Shanghai, stay there for 5 days and then go back to France.
For the first time In Shanghai where we just catch another plane, without leaving the aitport we dont need a Visa, correct?
When we come back from Tokio to Shanghai after 5 days we can apply for the 72 hour visa free visit?
Thanks. These rules are so hard to understand.
So this roundtrip (France - Shanghai - Tokio and Tokio - Shanghai - France) is possible without a tourist visum?