You see, what ruined this series for me was the characters. Most of the characters are presented as onedimensional, with each being from x side or the y side or the z side. If they're particularly important characters, they will have a trait or aspiration which will rule their personality without giving them any further complexity, like friendship, family, power, greedyness, psychopathy, etc. Each character will operate under one role and that role only and they won't have any sort of trait that would give them a more complex and more human personality. Thus they feel very onedimensional and they were hard to feel any attachment to, because you constantly knew which is their one and only priority. The two characters the series treats as the main characters are pretty much the only two people that feel like more or less people, because they do things that occasionally clash with their goals, but I didn't personally enjoy their portrayals.
One of said characters is the main character, Angelo, or Avilio as he's known by everyone other than a single person. Of the two I'll talk only about Avilio because the other character doesn't enough depth to live on its own. I didn't like Avilio's character. For the reason that he doesn't seem to have any flaws other than him being emotionally damaged and having no desire to live life outside of his revenge. But these are not used at all to impede his goal, so he's pretty much a Jesus character. Avilio manages to constantly scheme and use characters to his purpose, planning things just the right way through all adversity and always coming out unscathed 100% of the time pretty much because he's the main character who delivers his vengeance. There's not really any time where things seem to remotely go against him specifically. The group he is in may suffer. His "friends" might be in a disadvantageous situation. But as far as Avilio is concerned, he never seems to be at odds for the vast majority of the series, even in a situation where he's at a complete disadvantage. The one very good moment in the series, is when that actually finally happens, he finally is forced to do something he doesn't want to and has no other choice and can't create bullshit out of his ass. Which I can't talk about because it would be spoiled. Outside of that one moment he always seems to be the perfect man who's gonna reap vengeance and deliver his justice. Which isn't a good thing. The only thing flawed about him is his goal. Nothing else. As far as his actual personality goes, Avilio never displays enough emotions to engage his character from a viewer's perspective, merely showing short glimpses of very minor reactions that would build his character more as a person. Avilio is portrayed as a silent husk of a person, which makes him as engaging as a toenail, with the personality of the doorknob to boot.
I'm not gonna deny that the type of person Avilio is does deliver this series' point, but a good drama should have some way to make me care about its characters. And the main character is bland, and everyone else seemed even worse. For instance, in a setting where there's 3 big families from the mafia, other than power "levels", I can't tell you any thing that differentiates them from one or the other, except for their leading dons which are onedimensionally portrayed characters. And this is in a story where all of these families are relevant to the world and Avilio's goals, in a series where common traits might hint at things to exploit which would help Avilio. This is in a story where you should also empathize with another character that aspires to constantly help his family, with his family's only saving grace being... that they're related? I can't honestly find any side to root for, for neither a moral reason, or a reason based on ideals or anything of the sort. Everyone seems to be after the same thing, which is power and money. I'd classify henchmen that sacrifice for the family into the power category as well, because they might not be doing it to promote their own, they're doing it for the person who they're supporting. If the story is a drama, there's nothing that compels me to interact with the characters, because they feel too shallow.
The story is simply about revenge. But I can't be engaged in a story about revenge when I simply just don't care about the characters and simply see them as set pieces. Yes, there are one or two things that aren't purely minded towards that goal and it does present revenge in a negative light. The best moment of the series is when finally the main character has to do something he just simply would rather never do, which I've mentioned before. But otherwise, it's a story about a guy who lost his family killing those who wronged him. Which is a standard plotline. And any elements that could make it interesting, its setting, its characters, everything is not noteworthy.
However, despite everything I said, the story did have a theme that I felt it did get to go through. Due to its ending mostly and... that means I can only give you vague things to avoid spoilers and even then I can't guarantee there's nothing that is gonna give away how the series will end in this paragraph. So I advice you to just to skip this whole paragraph in order to avoid spoilers if you'd rather stay clean. The theme of the series is about living in the past. If you let your past define who you are today, once everything that kept you in the past is gone, you're a nobody. If that's what builds up your life, the only option left once all of that is gone is to move on. Power means nothing without the reason you've aspired to it. I know how vague all of this sounds, but I can't get into it any deeper. It's far bleaker and vague, however, this is the essence of it. Take it or leave it.
In terms of action, I wouldn't call this series an action series as much as I would call it revenge porn, with everyone falling in the front of the one and only God, Avilio. Most of the action is comprised of shootings but there's one or two more brutal moments, which I'll just leave unsaid since they bank on the shock factor to an extent.
In terms of artstyle, the series is mostly fine, but the overall color balance with cold colors and low saturation didn't really help make the world more vivid for me. I think the world is too bleak and makes the story too serious. Otherwise, I like the overall art, but for once I wish a series would be a little more colorful. In terms of sound, I found nothing noteworthy to be said, negative or positive.
91 Days was a dissapointing experience for me. Because, it had very little going on for itself and it failed to make me care about its world, its characters and its events. While I think it did succeed in its theme, there's a lot of moments that just didn't help and seemed to serve only simply as revengeporn. So ultimately, I think 91 Days can be a fun ride if you just wanna see how a character dismantles organizations in order to achieve the justice he thinks he deserves, and you just wanna see how he succesfully and consistently does it. Basically if you think the revenge porn aspect is the only thing that will carry you through. Because otherwise I can't really recommend it on any other factor, perhaps its theme, but I can't assure you that it will pay off for you. I think the series was ruined by character portrayal, and how nobody seemed to matter and have any value to the story. There were only a few people that really mattered and were focused on, and they aren't particularly engaging either, they're just there so that Avilio the doorknob wouldn't just boringly sit there and brood. The show lacked tension because the main character seemed to almost always achieve his goals, the show lacked engaging characters, because they were one dimensional, the show lacked drama, for the same aforementioned reason. It was lacking in a lot of ways, ways which make this anime hard to recommend. So if you think the said things would be roadblocks for you too, I suggest you avoid this. 91 Days is one of those series that I think are enjoyable only if they're exactly what you're looking for.