If the Chinese and Russian have a joint Exercise in Sea of Japan, then their "target" is not Japan itself, it would be most definitely be United States
And whatever the Chinese do, it did not change a damn thing, either Japan nor US gonna back down that easily, Japan will not abandon Senkakus and US will not abandon Japan. It would take more than Exercise or even War to break the Bond between Japan and United States.
I don't think this is any kind of provokation or whatever in the same sense. It's just an exercise, they can exercise anywhere if they imagine Japanese is their enemy, so, that should not attract more attention than any exercise PLA done in the past and Beyond.