Is it possible to get CHN visa in JPN as a EU citizen?

Hi, I’m afraid it is rather difficult for you to get it from there because temporary visitors in Japan are usually advised to make the application in their home country.

We are EU citizens travelling for the last 7 months. We were in Japan on a 90-day tourist stamp and there was no problem to get Chinese visas in Osaka (June 2017). They didn't ask for it, but we added a note to our visa application explaining that due to our travelling plans it wasn't possible to get the Chinese visa in our home country. I'm pretty sure they didn't even read it though. They did however require a full itinerary for the whole stay, including means of transport between the cities. We booked stays on booking.com at hotels with free cancellation and just stated "train" for each transfer between them.