I'm a US Citizen, with a current US Passport.

Please advise if I need to obtain a tourist Visa for the following trip itinerary:

Delta Airlines - July 21st, 2017 from San Francisco to Shanghai (arrival on July 22nd)
Japan Airlines - July 25th, 2017 from Shanghai to Japan
Japan Airlines - August 2nd, 2017 from Japan to Shanghai
Delta Airlines - August 3rd, 2017 from Shanghai to San Francisco

Thank you!!!!