Do I qualify for 72 hour Visa if...

I work for an airline and always travel standby. I am coming from U.S. to Shanghai arriving on Sunday evening around 9pm and I will be standing by from Shanghai to Narita on Wed morning at 9am? I have a valid passport AND proof of itinerary with the airlines along with my Airline ID but am not confirmed as I fly standby with my job. Will they let me out of the airport in Shanghai for the 72 hours or less with this?