Chance will NOT end up being the Big Bad.In Jisei's epilogue, we saw her talking about the USB. In Kansei's epilogue, we saw her arguing with Liam evilly. However, the only thing we learned was that A) She's a bad guy, not the bad guy, and B) There's someone else, the person she was talking to on the phone. If anything, he's more likely her boss than her colleague, which would mean that she's not as high on the totem pole as it seems.
Kangai used to cut himself.In Kansei, a certain dialogue with Gurski and Kangai talks about how Mr. Auten might have killed himself, which leads to Gurski saying something like "Back then... didn't you...?" And Kangai's all like "Yeah, but I don't want to talk about it." It doesn't take a genius to connect it.
Naoki does not have kansei. At all.His Photographic Memory and time spent studying body language is impressive, but not supernatural, and it doesn't fit into the description of empathy-based psychic powers given in Kansei. And at one point he tells Li Mei and the protagonist that he's "not like them" before getting cut off. So it's very possible that he doesn't have any powers at all.