I’d like to know too. After the events of season 1, he can’t easily return because of sibyl system. Based off the pv, season 2 will most likely focus on Akane and her team. IF Ko is in the season it’s probably just briefly. ;w; This reminds me of a radio segment where Ko & Gino’s seiyuus talk about Ko and how he might fit into the series:
Seki - Ko & Nojima - Gino
Seki: He’d come running to their aid…
Nojima: “It can’t be helped.”
Seki: He’d say that. “It can’t be helped,” or “What the hell are you people doing?” And he’ll be out before they notice; the others will be like “Huh? He’s gone.”(laughter)
Seki: He’d be like Moonlight Mask
Nojima: That’s cool!
Seki: …when he comes and goes. And afterwards, he wouldn’t show himself completely.
Nojima: I see.
Seki: It’d be like he was never there. (laughter)
Nojima: But probably, there’d be a cigarette butt or two left from place to place.
Seki: Right, right. “Was he really here?” And then later, he’d be shown peering from behind a post…
Listen to the full thing here! (: