Can South Africans, traveling in Japan, apply for a Chinese tourist visa?

Yes, you can apply in Japan, but you need to apply the L visa through a travel agency, otherwise the embassy/consulate would refuse your application.

The documents are as following:
1. A valid passport with enough blank pages and 6 months validity; copy of the imformation page;
2. One recently taken, bareheaded, full-faced photo;
3. A Chinese hotel reservation certificate and a two-way air ticket;OR invitation letter
4. Visa application form (V2011A and V2011B);
5. Former Japanese visa

Good luck!

Thank you for the quick response Melissa!
One more question:
What agency can you recommend? I phoned IACE and they said it will take 1-2weeks to complete the application for South Africans. Can you suggest one who will take less than a week?
And just to confirm - We DON'T need a Japanese alien registration card ONLY the Japanese visa?

Sorry, I can not figure out which agency may take less time for your visa application. For single entry tourist visa, Japanese visa or your entry record to Japan on your passport is enough.