The manga is ten novels long with a extra book on the movie that Sana-chan did. It like the anime but moves faster and is A LOT shorter. For example, in the first manga, at the end, the Hayama thing is already over. In the anime, that doesn't end until the sixth episode. It's amazing how they can take a ten novel long manga and make it into a 100-something long series.
Click on the picture above of you want to go to the manga translations at Monochrome.