That still needs more evidence to confirm I'm afraid. Not only that we're not 100% sure about whether Tooru really knows Sera or not, but we are not even sure if anyone knows anyone. Gosho purposely made it seems ambiguous, and I doubt that it'd be for no reason. (Simply to troll us is also a "reason" too.)
By the way is it just me or does Tooru look a bit younger than his supposed age (29) ? It's just my personal feeling, because I don't have the chance to compare him with other characters, since random filler-case suspects have their own appearance design. I also cannot compare him to Vermouth (whose age is also "29") because she's a woman, and not Japanese. Anyway, I would fall off the chair if somehow he also had his age... "stuck"