I'm not someone who you can take advice from and be solid with that, so please take what I say with a bucket of salt ready to douse yourself with as I'll be speaking on my personal thoughts of your first chapter.
The Positives:
- Atmosphere: I really enjoyed the overall feel of what I read from the get-go. I'm one for proses that make me imagine vibrant images and I think you've done just that with lines like "The rain came down like it had a grudge. Alorihime pressed her back flat against the drainpipe, three stories above the street, and watched the neon bleed into the puddles below." Although I do believe parts of this line, the second half of it, could be trimmed in order to hit better, but that's just my preference, I think. (also sorry if it goes against the rules to take straight from the chapter itself, I'm new 'round here).
- Movement of Scene: This is going to be quite contradictory to what I'll have to say afterwards, but I really do like the sense of movement we have in the scene. In a high-stakes situation like intercepting the Dusk Fangs, I quite enjoy the feeling of go, go, go and keep going. Simple lines like these highlight this strength of yours "He spotted Alorihime and gave a thumbs up with his free hand.", "She pointed at the unconscious man, then at the floor. Put him down." They're quick lines, would fly by some people's heads, but they're effective to me, gets the point across as well as characterizes Alorihime and Bris at the same time, good job.
- Intrigue: You've built intrigue in the mission at the very first chapter, I'm not the type of person who gets hooked on much unless the fall under my specific genre but you've managed to catch me at the first and second paragraphs. You clearly have an imaginative strength that hooks when writing, so make sure you play on that strength.
These positives are not lip service from me, and like I said before, don't take it for the holy grail of advice, what I see in a positive light may be a turn-off for other people.
What To Work On:
- Dialogue: Personally, I'm the type of person who enjoys reading for the stand-out voices of characters in my favourite novels/shows. Their voices are instantly recognisable to me, whether or not they have a dialogue tag attached to them. I try to write this way, and I would like to implore you to play on this style of writing, which you've shown signs of. The voices of the cast are there, but not loud enough, if I can describe it like that. A positive example being; "I am holding." Himari's voice came back hot and fast and not even slightly convincing. "I'm holding so hard right now, Harlo. You have no idea how hard I'm holding.", gives off a strong impression of Himari straight from the get-go so that you'll know the type of character you'd eventually enjoy reading. But, once again, this is merely my preference in writing styles.
- Overloading: I noticed that in your first chapter I was in a bit of daze while reading it due to the amount of information we're given of characters, even if they just seem like brief descriptions to you, I'm not sure if others would agree with me on this, but maybe spend a little more time breaking up the short intros to each characters and then moving onto to the next. An example of what I mean by overloading; "Bris Blaik rounded the corner of the adjacent aisle with a Dusk Fang guard draped unconscious over one shoulder..." (and the rest of the paragraph). It confuses the reader more than clarifies their role and how they act. My best advice for this is to Show and NOT Tell this time around, while I think telling can sometimes be a good tool in storytelling, it is sometimes detrimental and should be used as a double-edged sword. This line highlights why I believe that; you can instead simply show Bris grinning and the readers can infer from there.
- Grounding: Something I noticed with the mission scene was the lack of grounding I had while reading it despite the many descriptions of senses. Personally, I don't have the skills to discern why I feel like this but I believe it's because of how little room you give the scene to breathe properly (I know, I know, I said I liked how paced it was). Maybe this point is weaker than others, but that's how I felt reading this chapter.
Overall, I enjoyed reading this first chapter and I may or may not read the next ones you've already posted, and once again, I'm no professional, just a self-taught writer who's beginning to travel around Scribblehub. Take the tub of salt and double it for these advices.