72 hours qualify?

I hold a US Passport. Flying to Sydney, Seoul, Hong Kong, Tokyo, Beijing. i am flying to Hong Kong (from Seoul) on October 20, then Tokyo on October 22, then Beijing on October 25. My flight arrives in Beijing at 6:35 pm on October 25 and depart to the United States on October 28 at 4:50 pm. Does this qualify for the 72 hour free transit?