If you're reading this paragraph then I'll assume that you did. Do you like the theme that the anime has presented? Yes? Then you should give this adaptation's manga instead a try. I'll explain why, as I've done a check up on the differences between the manga series and the anime series.
The anime's story tried to strengthen the cutsey/moe-ish factor of the show by a fuckton. To do that the show has done certain changes which left out a bunch of scenes where the conflict between some characters has been underwhelmed or totally removed, some events were changed to be more lighthearted or simply replaced with some more slice of life-ish moments. Some moments that define the mental state of the main character better as well as some mental breakdowns were removed from the show. Some events were rearranged to fit the cutsey aspect of the show better and make it be more lighthearted. And on top of all that since they thought the cutsey factor will sell and because we've got girls in the show, you like girls right???, they also added a beach (a pool episode but not really) to it. And due to all of these factors this, the anime will feel lacking and kinda skewered.
In order to succeed in selling a character that lives in a certain state of mind, you've gotta detail their state of mind as much as possible and the anime's description of the main character's state of mind is simply... accepted by her peers. It is never really explained properly why. The explanation given to us is really, it cheers us up. But in the manga it actually is a little more complex than that. I can't go into more detail because of spoilers here, but note that the manga has given more important details to make her state easier to understand and accept. Her state of mind fuels the tragedy in the series and her struggles. All these things to give depth to her character, and even the characters around her since the effect and the impact her state has on them is also more explored in the manga, all of that, replaced with cutsey moments.
The pacing of the series is all damaged, in order for the anime to get serious due to all the changes they've done to the source material it had for a good while to appeal to flashbacks in order to describe the current state of how things are, making it seem as the worst has passed and they're making the best out of a bad situation and living somewhat casually at the current time. In the manga, the pacing is better. And the worst part is that the pacing makes the final events of the series feel completely convenient, from a casual watcher of zombie series' standpoint. There are some things will feel awfully convenient happening. Like, no, stupidly convenient. Like, shoplifting something, being caught, and you asking "Can I steal this PLEASE?". And they're like, yeah sure. Then you leave, yay, free shit. I again obviously can't give details on this, because spoilers.
So what can you expect from the anime itself? A story that doesn't describe its characters and the struggles they went through properly, banking on the fact it's cute and hoping that it's cuteness will be a catalyst to an impactful ending, banking on a couple things that are very likely to market. Is that the same case from the manga? Well, I can say the story takes itself more seriously, and things won't feel nearly as convenient there. There's some skipped content in the anime. (a bunch of chapters actually, consecutive even for a bunch of them) There's a character in the series (The dog) that is merely an episodic chapter in the manga series which in the anime is pretty much part of the main cast. The dog is anything but an integral part of the group. And something that will happen to the dog is explained way better rather than not at all.
To put it quite frankly, the things the anime has done quite well are its intro that gets progressively more fucked up as the series progressed, which I thought was a nifty touch, but I can't say I am a fan of the moe artstyle, or the slice of life-ish moments that took away development from the characters and the group as a whole the manga had. Anything else? The serious moments were done mostly well, but the series is mostly killed by its pacing. As I've said, when it's not in flashbacks, it seems like they're living somewhat of a peaceful life and the worst has already passed, making it all the more ridiculous how by its end, everything that will happen will simply feel convenient. And while the manga also tries to look cute, it does not do it at the cost of telling a more complete story about the characters.
If you want a more solid story with better characterization and better focus on the characters and of the theme this anime has, just go for the manga. The manga is decent, it explores the impact someone delusional and why they're delusional overall impacts the group, and the view of everyone on it and the impact this has on them. The anime tries to exploit this mental state as a tool towards building slice of life-ish moments that took away from the story. The manga tells a more natural, better paced, not nearly banking as much on the "please notice me I'm cute" factor. The problems of the group and characters are solved with less convenience even though there's some of that inside of the manga too. The world will be described better than in the show and in this particular type of setting, knowing the dangers of the world is very important. Overall I'd say the anime adaptation was an adaptation mostly ruined by marketing tactics. The manga series while not incredible, it still does a decent job with its theme and it uses its strengths mostly right.
However, if you're not interested in the theme or just don't want to bother with the manga, you could just avoid this series entirely. The reason I compared it with the manga so much is to explain why the adaptation was bad and if you are really into the theme, you have a far better alternative. I can't recommend you going into the anime for any reason, in good faith, when you have a better alternative for the same story in a different format.
