User blog comment:Omega natsu2/Chapter 369: The Place Prayers Reach, Predictions./@comment-2214433-20140129011112/@comment-1359322-20140129091743

Well we have only seen Natsu interact with 3 of the 9 members, and out of the 3, 1 showed that he seems to know Natsu. So there might be a possibility that there are other members of the 9 Demon Gates that knows Natsu. Perhaps the best way to know is to have Kyouka meet Natsu face-to-face.