I'm an American flying from Japan to Beijing to Chicago, with a 68 hour layover. Do I qualify?

2 of us (Americans) will be flying from Chicago to Tokyo to tour Japan for a week. From Japan (Haneda airport), we're flying to Beijing and will be there for 70 hours (Wednesday night landing at 8:50 PM) and depart for Chicago on Saturday at 4:10 PM. We'll be there about 70 hours, do we qualify for the 72 hour free transit? What will we need upon landing at Beijing International airport?