We hold US Passports, on a cruise Hong Kong to Tokyo do we need VISA for Shanghai?

Taking Celebrity Millennium cruise in April 8, 2017 departing US flying to Hong Kong for 3 days, going to Taiwan, Okinawa, Shanghai (06:00 to 10:00 P.M.), Nagasaki, Kobe, Mt Fuji Yokohama to Tokyo on the cruise. Departing Tokyo on April 25, 2017. Do we need to have a VISA in Shanghai? Can we travel independently from cruise port Baoshan to Shanghai or do we need a guide?

Thank you