Would we need a Chinese Visa, or would we be covered under the 144 hour exemption?

Flying from the USA to Shanghai to do an 8 night cruise (Sep 15- Sep 23). Not sure if the flight will stop in another country or not before arriving in China, if that matters.

We might wish to stay in Shanghai for maybe 2 nights or so. We would then go to the port at Shanghai, visit 4 cities in Japan, and return to Shanghai. Once back in Shanghai, we would fly back to the USA.