Board Thread:Questions and Answers/@comment-4726368-20130508221557/@comment-4105472-20130608074831

In the episode 4, the other coach for Shinsei Inazuma Japan (not Kuroiwa but the other one) said to Gouenji he knows everything about Kuroiwa's past.

I think this also kinda means Kuroiwa is Kageyama. But we may need more infos to be sure they're the same person.