LOS ANGELES - LAYOVER SHENZHEN- THIRD COUNTRY JAPAN US PASSPORT

PLEASE HELP!! I have a flight from LAX to TOKYO, JAPAN. I have an 8 hour layover in Shenzhen, but the final destination is TOKYO. Do I need a Chinese visa? Or an I exempt from getting one, and will have no trouble tranisiting through Shenzhen. I have no plans to leave the Shenzhen airport as well. I've been reading many different sides on the internet, and will call my carrier to confirm; but I need help. I have a US Passport/US Citizenship.