Second season? They ain't smart enough for no second season. That's why you see 13-ep generic harems and shonen fighting series with a plot indistinguishable from every one that came before them.
Well the prequel noel is getting animated, but that's ALL anyone knows about it I think. No news about if it's an OVA a TV series or a movie, well either way once it does get animated it means more pre-loli body Shinobu which is great.Assuming the second season wouldn't be the prequel novel, the sisters WOULD have more screen time as they each have a book dedicated to them. Their also very incest heavy!
As far as I know, every character of the first season has a second story, and the sisters have theirs too, that's why I think there's enough material for a second season.
that doujin had 2 more parts that followed.
Since you already did the first Fire Sister doujin seen here, http://trinity-translations-team.blogspot.com/2011/06/release-56-onegai-fire-sisters.htmlMight I suggest the other two as well.http://exhentai.org/g/324389/c298dd398c/andhttp://exhentai.org/g/277078/74fa4f923b/
I spoke with Catharsis (the Translator of this doujin and member of TeamVanilla & Sharpie Translations) and he says that he IS working on the Translation Script for the sequel, but it will take a while since he's busy and it has MORE dialogue than the first one. Let's wait patiently...