episode 12 answer this question
Well considering the season ended with the graduation scene it appears they've cut out around 8 chapters worth of content, with the last scene hinting towards the new charactors introduced in the manga. So if there is a second season it won't be for a while as they don't have enough content.
They did a really good job in adapting the manga, dispite it's many changes, like the way Megumi and the dog was done was allot better than the manga, and made it better than the original sourse in many ways. The dog was a one or two chapter after thought and Megumi was only in the first few chapters, so you were not as attached to either charactor as much, same for Miki, she came in around chapter 10 so by having her introduced from the get made her feel like a important member from the beginning, instead of someone who has to be moulded into the group.
Hope we get a second season, this is normally not my cup of tea, the zombie thing or the cute high school girls thing. But somehow this turned out to be more enjoyable than I thought, the manga and anime.