Make your way over to #10a, who wasn't there the first time you went through.  You can use techniques now, so it's a good time to customize Resta and any other tech's you normally utilize. 

Finally, go over to #10b and talk to him.  Next, you might want to cast Shifta/Deband on #10b and yourself.  Look around and keep talking to #10b until the final battle occurs.