It's a post-apocalyptic world zombies everywhere. So where those kids coming from?? Maybe, only few survived but suddenly everyone has a job? Kids? Well, maybe the "good Randall" help them survivors, but in only 3 years?? They produce lots of kids? So Yuki can teach them in their old school? Ha?? What happened with bad Randall? What's up with the infection that Randall made? Why they need to do such thing? This is too rushed and we need to know more about Randall than those girls. And in the end whose Yurii's boss? So many unanswered questions in the last chapter, it feels unsatisfied. After so many journey we've been through together with those 4 girls, then suddenly they are... growing up and doing normal things once again. Good, for them though. It's their wishes, but come on! The questions remain unanswered.

I don't think we are. I've read up to 24 and I'm done with this boring crap. There are a lot of issues here to cover and I'll avoid actual spoilers.
You're telling me a string bean from the track club has the weight behind her to smash zombie heads in with one hit with something that looks like a fold-up shovel (more like a glorified spade, the one-handed garden variety)? NO! Zombies are attracted to the light from a glow stick (they watched it fly through the air in one panel)? BS! Zombies cover their ears when a sort of portable alarm is sounded? What?! Nobody has tried going inside the school for supplies? Doubtful! Only girls seem to have survived and there are no males (not a spoiler, categories and genres give that away)? Beyond improbable!
There are many more, but I'd be giving away too much. This manga is incredibly child-friendly, while incredibly boring at the same time. Nothing ever happens. The only part that could have been interesting after seeing this was the psychological aspect, but there's only a page or two worth every 5 chapters aside from the first 3-4 chapters (an exaggeration, but just barely) and it NEVER furthers character development. This is like survival for people who have all the time in the world. In fact, I'm having a harder time surviving it's lack of plot.
I tried to get into it. I really did. Normally I don't mind a manga like this, but NOTHING HAPPENS! It may as well be episodic. Here's a better summary:
Oh no, the world has ended at the hands of some slow-walking zombies! A few girls pretend zombie apocalypse never happens. To their surprise, it works! Aside from the occasional zombie who's weakness is basically a girl swinging a flyswatter, their carefree days of living inside an abandoned squatter's den starts! Time to play "academics no longer matter since much is taught on the basis that electricity will still be running, but we'll play school anyways!"