I was thinking the same, might be something that's brought up once we find out about the 22nd Feb Ninja disaster since Kawado seems to have a lot of connections to it while not remembering much
Yo first his eyes turn to puzzles and now his brain!? In his final form he'll probably consist only of puzzle pieces (altough sometimes it looks like he already does but you get what I mean)
Seems like Munchen's philosophy is that everyone exists so that the striker can score and I'm already creamin at the idea that that striker could one day be Isagi