Oh... wasn't it obvious that he was Otcho? I mean he noticed the little finger arrow on the shounen magazine, which he pointed out to the seller - that gave it away that he was from the group (that was probably the inspiration for the insignia). Then the whole training with the monk, we knew Otcho disappeared right? So that confirmed it. I mean c'mon they even say he's Japanese.
Anyways, the fact that Kenji got in touch with him! How'd he track Otcho down??