Quote from tsuto
Well, the shoujo ai part is for comedic purposes I guess, and so far the anime is a good adaption, with slight differences, but both manga and anime are based on a light novel, so I don't really know how it's. Also, it's not exactly necessary to read Index, but it's a plus, since you get to see some situations from a different point of view and that is one of the most interesting thing they both offer.
Thanks for the explanation~
Hopefully the manga won't have as much shoujo-ai/fanservice as the anime...