well, the pieces of the puzzle are all in place at the end of episode 11. we have Haruka and Gai... and with Inori captured, Shu will be more curious why all those things transpired..
I got a gut feeling that the "other" boy in the picture was not actually Gai but that new dude with the King's power..
but Gai being the "other" boy would make perfect sense since he somehow knows who "Mana" is.. I have a gut feeling that..