Quote from an NHK news report:
"The Japan Coast Guard says the JAL plane collided with one of its aircraft immediately after landing at around 6 P.M. on Tuesday."
"Immediately after landing" doesn't suggest a midair collision to me.
After seeing more photos and videos of the JAL Airbus 350-900 wreck, I wonder if JAL was still partially in the air when it hit the smaller Dash 8. The nose of the 350 is smashed in and the nose gear and the right landing gear are missing.