Am I eligible for 72 Hours Free Transit for staying Shanghai?

Hello, I am U.S. Citizen and will visit to Shanghai form Nagoya Japan by the China Southern Airlines direct flight and will return to the same port, as the detail schedule below.
CZ380 / 21 October, Arriving Shanghai at 1050hrs (Form Nagoya Japan)
CZ379 / 23 October, Departing Shanghai at 1755hrs (To Nagoya Japan)
* Total 55 hours stay in Shanhai

My trave paln is 'Nagoya-Shanghai-Nagoya'. If I will NOT be eligible, NOT considered as 'Transit', please also advise the case if I travel as 'Nagoya-Shanghai-Tokyo'.

Your kind advice will be appreciated. Thank you!