Three main girls from the Manga "Fuuka" by Kōji Seo
Fuuka Akitsuki, Fuuka Aoi, and Koyuki Hinashi
I have made a post about this amazing manga/ anime a while back while it was still airing. Feel free to read on it if you want to learn more about the Manga and the story. Fuuka Aoi does not show up in the Anime due to it's alternate ending but the Manga is still on going.
UPDATE: MANGA IS CONCLUDED