Is it possible to get a tourist visa if I only have a single way ticket?

Do you hold a Japan passport? Japanese nationals are exempt from a visa to Mainland China for 15 days, if you really don't know how long you will stay in China, you can first go to Mainland China and stay for 15 days without a visa, then apply for a China visa at the local Exit-Entry Administrative Bureau of Public Security Bureau. If you want to get a China visa in Japan, you have to apply for it through a travel agency.

thanks for your reply !
actually I have a french passport. so I definitely need a visa

If you have a French passport, you can submit visa application directly to China embassy or consulate in Japan, you can also apply for visa through a travel agency.

In fact, the round-trip flight ticket is not mandatory, the applications is considered according to the merits of each applicant. If the visa officer is afraid that you will overstay in China, the round-trip flight ticket will be required.

One of my U.S.A friends get a single entry L visa by providing his passport, filled visa application forms. The air tickets and hotel reservation are not required.

Do you have a long-term Japanese alien registration card valid for at least 6 months? If you have it, the visa officer won't doubt you will overstay in China.

I have an alien card but it will ends up when I will go to China. I spent 1 year in Japan, then I decided to go there instead of going back to France, so I wont go back to Japan after China, but to another country in Asia, for sightseeing.
anyway, I will explain that to the officer at the embassy, and see how it goes.
thank you very much