Quote Originally Posted by Nadouku
This makes me wonder if they are introducing some new characters in the Railgun series, and whether or not Touma will make an appearance as either a side character or cameo, along with other supporting characters.
From what I remember, Railgun a series of side-stories that happen before index's arrival. I would imagine that Touma won't be on such good terms with Misaka, especially after that Aztec Priest incident. Their encounter in episode 1 hinted that they knew each other though, enough that Touma knew when some thugs would get their asses owned if he didn't lure them away.

At that, I'd imagine Touma would play a part, albeit a more minor one.