(Part of a Review Swap)
About Style:
Foreword: Of course, all these things are simply observations. Style is one thing that is difficult to change in the middle of any novel, so just think of these as a reader's perspective rather than suggestions.
- I like how you used dashes to show the difference between a phone call and normal speaking, but I was kind of confused when the main character also spoke in the same style while talking to the Captain in person. It looks like this is used regularly throughout and I don't really understand its purpose. Personally, I just write in a strictly traditional manner, utilizing only quotation marks and ending with "said the character" or variation.
(*TLDR; quotes are a bit confusing with dashes instead of quotation marks. Not sure what those signify*)
- I also noticed that the novel was written in a script-like format, the date and place present without being a sentence and utilizing tumblresque signification of action (such as when the wife *Smiles*). I personally never read a book in a similar format, but there's nothing wrong with it. I believe that readers of more traditional books (such as myself) might be a bit repelled by the casualness. (*TLDR; The casualness of the writing may be unsavoury for some. Of course, that's a personal preference*)
About Plot:
Alright, I've read a little bit more of your book. Up to Chapter 3 to be more specific. I think I'll skip to the final chapters to see if I'm giving unuseful advice, but here's what I've thought about it:
Firstly, the pro: I think the fight scenes are well choreographed and interesting. There's always a lot of action happening and it really feels like a yakuza action movie. I still feel like the wording could be edited further (and there were a noticeable amount of grammar mistakes), but the content is definitely there. Solid action. I also liked the protagonist, Kazuki Oni Yamato.
Secondly, some feedback: I thought the plot was pretty generic, though maybe the plot isn't the main focus. I mean, you get what you look for and it definitely was a book about the yakuza, all the cliches included.
So far, I would personally give around 4/10. It definitely improves as it goes on, but I don't think it's for me. But hey, it seems that a lot of people are enjoying your book (56K views are a lot!) and that's all that matters.
Final Evaluation:
After reading the final chapter (which was a bit shorter which is why I was able to write the review so quickly,) my rating for the book just went up to 6/10. Wow, the improvements are stellar, from grammatical correctness to the dialogue, everything's improved by quite a lot! Now, there are some criticisms and so, these are my final thoughts.
Grammar: There are still some minor grammatical inconsistencies like sometimes the suffix 'san' being capitalized (Suzume San) and sometimes being connected to the names (Yamato-san) as well as 'Ojosan' sometimes being capitalized and sometimes not.
Cultural Aspects: Now, I need to clarify that I am not Japanese and may you are. I'm just taking a stance from the perspective of the readers. From my limited knowledge, the book can't help but seem a bit like a non-Japanese person who wrote a book about Japan. Again, no offence. From the names (Yamato, Suzume, Jin) to the locations mentioned (Shibuya, Tokyo) as well as the usage of the honorifics (saying -chan to someone that doesn't know you), it can feel a bit inauthentic. Not saying you need to change anything, just something you might want to look out for.
Format: There's definitely a shift in format from the first few and the last few chapters, mostly noticeable in the quotes and signification of location and time. Now, it's definitely for the better, but if possible, it'd be great if you could edit the previous chapters to be more in line with the current standards (unless webnovel.com doesn't allow that).
Conclusion: I think this is a great start to your portfolio as a writer and there is a great deal of audience engagement, meaning that there is a market for these types of stories, but I believe it could be further improved, especially in grammar.
Overall, a pretty solid read. Personally 6/10, but that's just my personal preference and this book is probably not for me. I see a lot of 5 stars and four stars reviews, so you're doing great!