This is not Hayate from StrikerS. It's Hayate from A's (2nd season). She's still adorable though. Hayate is my 2nd favorite character (Vita being my 1st and Fate 3rd). Adorable, adorable picture. Definitely a favorite.
Well, actually, it could be from StrikerS after taking a look at her apparent chest size, but her legs don't look as developed as they do in StrikerS, so that's mainly what led me to think it was from A's. It could be from either, though I doubt Hayate's chest is that developed in A's. Hmm. Still adorable though ^-^