We cruise Hong Kong to Shanghai where we stop for 2 days then sail to Sth Korea and Japan

We have Australian Passports and will want to go ashore for each of the 2 days while the ship is docked in Shanghai. The 28 day cruise will finish in Japan on 30 March. Do we need to apply for visas for Shanghai or does the visa exemption for 72 hrs also apply in this situation for Australian passport holders?