I am a US citizen currently traveling in Japan and need to enter Shangai China from Japan for 2 days

I am in Japan, I have a valid US passport and had previously had a Chinese visa, which is expired, but still in my passport as reference. It is the 11th of January, 2016 and I have been requested by a Chinese supplier to attend a meeting at the last minute. I need to arrive on the 18th of January and will depart on the 19th back to Japan. I cannot surrender my passport for normal processing as I require it while in Japan and will be traveling to other countries in the meantime before I would depart for China. This is for business