I think that everyone who has some cultural knowledge can easily see why Akechi has a crow theme- crows are seen as intelligent, mysterious birds who are associated with death, all of which also fits Akechi's character.
However, recently, I found out that in Tokyo, crows have a much different reputation- that of an nuisance, an annoying pest, one akin to rats and cockroaches. In the late 90s, the government told the inhabitants of Tokyo to throw out their trash in see-through, more easily biodegradable trash bags- but they haven't considered that these bags would be very easy for crows to open, causing a boom of their population.
The asian jungle crow is a large and fiesty bird, much more so than the smaller species we know from Europe and North America; This species gets paticularily aggressive during the breeding season, and will swoop at people who get to close with no hesitation. They steal coat hangers from balconies to use as nesting material, cause power outrages by making nests on top of powerlines, steal food from people eating outside, and can form huge, noisy flocks as they come to roost for the night- not to mention that they of course open up trash bags and toss out the contents while looking for scraps to eat.
In short, they are a nuisance to humans. It's not suprising that there have been campaigns to cull their population, which peaked in 2001. Outside of putting special nets on bins and garbage bags, crows have also been trapped and gassed- now only about 20% of that 2001 population remains, but the crows are still present in Tokyo.
I focused on this specific crow population due to its location- Tokyo, which is where the story of Persona 5 takes place. The developers have put a lot of work into making the game Tokyo as similar to its real counterpart as possible, to the point where you can visit a lot of the in-game locations irl and recognize them instantly- there's plenty of photos online from fans visiting real-life inspirations of in-game locations. Tokyo in itself is a sort of character in the game as well, given how important it is in the endgame.
Okay, but what does it have to do with Akechi? Well, quite a lot, in my opinion.
I wanted to bring up this specific quote about the crows of Tokyo- it's just an opinion, so don't treat it as gospel, but I think that it's an interesting starting point:
Just as the crows, Akechi has been seen as a societal nuisance- someone who disrupts order just by existing, someone who should've never been born in the first place. He spent his life living on the metaphorical outskirts of society, first with his mother and then as an orphan- he was a societal reject due to his status as a fatherless child of a sex worker, and then as a child who lived in an institution. Akechi lived on "scraps" as a child- his mother was likely poor and couldn't afford anything beyond strict necessities, and childcare institutions in Japan are also pretty underfunded; So Akechi had to make do with what he could get. He still managed to persist in big part thanks to his intelligence, just like the crows managed to survive in the metropolis thanks to their cleverness and willingness to use every opportunity they had.
However, the things Akechi was willing to do to get to where he is at the time of the game went against the rules of polite society- just the fact that he, as an orphan and a child of an unwed single mother, wanted to claim a higher spot on the societal food chain, went against the norms, because he should've just shut up and know his place. That's kinda what the crows do as well- they go against the societal order, they're loud, they make mess, they're not afraid to attack humans- and while they're birds, animals who are not malicious and merely trying to survive, a lot of people see their behavior as mean-spirited. And while Akechi's actions are inherently more nuanced due to the fact that he's a human being who's capable of making moral choices, one can argue that in a society as opressive and inherently unjust as the one potrayed in game, can't his actions be somewhat justified, or at least understood? Given where he started in life and what he went through, is his desire for a better life that unreasonable?
Societal conformity in an unjust, corrupt society is a huge theme of the game. I wanted to once again bring up the quote I included above- crows are seen as pests and nuisance, because they don't conform to the kind of behavior humans demand from wildlife that lives in their vicinity: Be cute, small, harmless, and preferably unnoticable. Crows are none of that- they're huge, loud, bold, and their natural behaviors cause chaos in a seemingly harmonious human society around them.
I think that Akechi would heavily sympathize with them and feel a strong affinity for them, which is why his Metaverse alter ego is so heavily based on a crow. I know that he uses the codename Crow for both of his alter egos, but let's focus on his second one, which also takes a much heavier inspiration from the bird when it comes to the design.
Crow is heavily themed around chaos- we have the "call of chaos", of course, which Akechi uses to cause societal disruptions of all kinds, and during Hereward's awakening, he gleefully says that he will "spread chaos as far as the eye can see". Akechi loves being disruptive, he loves causing unrest and upsetting the shaky balance of Japanese society- which is similar to what crows do in Tokyo, at least metaphorically. Akechi seems to be pretty fatalistic, and sees himself as someone who was made "evil" due to society's mistreatment, and someone who cannot change- in some way, that also parellels crows, as their "problematic" behaviors are simply natural to them, not something that can be "taken out" of them. Behaviors like foraging through garbage and attacking people, as undesirable and repulsive as they are to humans, are simply inherent to how crows behave and live; I feel like Akechi has a similar approach to his own behaviors and feelings, mostly related to his anger and other and emotional problems- no matter how much other people would despise him for them, that is simply who he is, and he's not going to feel remorse just because he's a "bothering" people who would reject him anyways.
I also think that he'd be inspired by crows' perseverence, cleverness, and persistence. Even after humans tried to kill them all, get rid of them and regain the balance in society, the crows still survived and cause chaos today just as they did decades ago.
More of a sidenote, but the largest crow cullings in Tokyo took place in the early 2000s- assuming that he was born and raised in Tokyo, Akechi would've been a child then, and I can easily imagine this impacting his psyche in some way. He already probably knew in some capacity that his society doesn't want him, and now he got to see what it does to its non-human undesirables- something like that can shake a child pretty hard, especially if they already liked crows (which is possible, as Akechi would be well familiar with them if he grew up in Tokyo at the time) or could somehow link their own status to that of crows in some way (and Akechi is canonically very intelligent, and I don't doubt that was also the case when he was small).
(Source of the article is here, the title should be relatable to any Akechi apologist lmao)