User blog comment:Miskos3/Fairy Tail Episode 263: Tartaros arc: Soaring in Ishgar, Review/@comment-4963128-20151213164529/@comment-2214433-20151214214536

I mean, I could be wrong, but all the announcements came from the -same- director and were posted on the main anime's website. When you look at the poster, it has the same Fairy Tail Logo. The announcement itself was the same as when they announced Tartaros arc. While that's not a confirmation in itself, MAL lists it under the main anime as well. Plus, Zero as a separate anime would make no sense when they didn't even bother restarting the episode count for S2. I'll be reaaaaaaaally surprised if it's considered as 'new', but again, I can see why people would think so. And if they can adapt Zero into 12-13 episodes long seasonal anime, then gg. We're up for some filler.