I am an American passport holder visiting Japan on business. and need to travel to China

I am a US Citizen, and holder of US Passport. I am visiting Japan on business and at last minute was advised I was needed in Dalian and Shanghai to attend business meetings in China. I will be spending two days in each city. My company has offices in Tokyo, as well as in Dalian and Shanghai. Is it possible for me to go to China consulate in Tokyo and obtain a visa to China? Since I will be attending meetings throughout the year in China, I would liike a 1 year multiple entry visa expedited.