so I've read three chapters and I don't think I need to read more. the quality is okay. there are little mistakes but the real issue is the uncertainty. I have no clue what tone you're going for. first half of the first chapter sold me on a dark gritty atmosphere.
however, starting from the second half, the narration, dialogue, and overall quality start to fluctuate. the narration goes from formal to casual/informal at random. dialouge goes from decent to mediocre at times. you introduce human modification and it's glossed over. then the number of cliches 1. perfect time to save damsel in distress 2. childhood friend 3. nameless thugs
S (the childhood friend) is ditsy at one point then she's not later on. she's been living there for 6 years, works in a gunstore, yet can't defend herself against cartoonish thugs. then you have zombies, which came out of nowhere. and finally you have both the MC's and S's complete indifference to their 6 year reunion.
this seems more like a rant, but i really enjoyed that first part, so I might be feeling a bit betrayed. I think you have your fundamentals down - you just need to decide on a tone abd stick to it. maybe plan a couple of things ahead and take your time building them as everything later felt very rushed.
