Given the timing of your layover (night), I think you have a pretty good shot at getting out of the airport. But, just to stack the deck a little more in your favor, I suggest you book a hotel room on ctrip (you can do this without giving them your credit card info), and print out the receipt to show to border control staff.

BTW, I notice you are coming from Japan. If you happen to hold a Japanese passport, you can stay in China for up to 2 weeks without a visa.