I kinda get what point you're trying to make here, but this is more about Kai character arc that the Hassaikai arc itself.
For Kai as a character I do agree on him not being as fleshed out as he could be (but disagree on the love part, I love him anyway so...).
The Overhaul arc as a storyline feels pretty consistent overall outside of thay specific part.
Besides you have to put this in the context of how it was published in the manga. Because by that point the Overhaul arc was at the time the longest arc of the series and go on for over a year which was a huge difference compared to everything else the manga had previously.
Besides is a known fact that Horikoshi wasn't emotionally okay during that time, and writing the arc with a very dark tone was not doing very good to his mental health as he said on interviews.
With that in mind it's totally possible that Horikoshi just wanted to be done with an arc that was going on forever and pass to something lighter in tone (main reason of why the school festival is almost cartoonish in comparison). That was at the cost of not expand on Chisaki as a character sadly.
As for the rest of your questions, it sounds like you don't finished the stoey of the manga so it might be spoiler so I couldn't talk about them without spoil some things.
ok so tell me if I'm wrong or overthinking this, but....
Does anyone else think Overhaul's ark was rushed and kinda half-finished? Why does every character have a fully explained back story that makes you love them no matter what, but we still don't know anything about Overhaul? Where did he come from? who are his parents? why does Pops' daughter not want anything to do with him? Is it just me? I feel like Pops neglected Kai as a kid. He's obviously mentally ill, and he had no care for that. where did he get his quirk theory from? When he said it, it sounded drilled into his head like he had heard it somewhere else. how is he connected to any of the AFO ark? he seems to be the adult version of Eri if she was never saved right? why did Pops find him wandering the streets? WHY?
I thinking about the shenanigans of Shindo and Cider 'fighting' over who claims Deku's love after the war (non serious promise, these two are just idiots in love for the same brocoli).
I bet their unofficial triple dates will go like this:
...
Shindo: Hey Zuku! I brought your favorite for the dinner (he ordered katsudon)
Deku: Yo that's so nice! (his eyes bright and his cheeks had a soft pink tone)
Cider: Izu! I rented the entire AM golden era movie compilation, we can have our movie night (he used Endeavor's credit car taken from Shoto to rent the movies).
Deku: Really?! Guys... you don't have to all this for me... (his blush intensifies)
Shindo and Cider feel their faces hot after that both exclaim "NO!!!" at the same time, promising Izuku they're happy to spend some good time with him. They proceed to eat the dinner, while Deku is totally ignorant of the small tension between his two 'friends'.
Later they're sitting on the couch with a movie playing on the tv, but aside of Izuku the others aren't really paying attention to the movies.
Shindo got an idea an he extend his arm over Izuku shoulder, getting him closer to his chest.
Yo: Great night don't you think? (ask to Izuku while giving Cider a smirk)
Deku: Oh... yes (a bit nervious because of being to close to Shindo's muscular chest)
Cider stars feeling angry but he looks at Shindo as if was saying "b*tch please" and then suddenly he drops his head on Deku's lap for the surprise of the others.
Cider: Izu can you pat my hair please? (he put big innocent puppy eyes)
Deku: Of course! (His smile is equally bright)
Izuku loves how fluffy and soft Cider hair is, as he press and tangles his fingers on the light blue locks for the pleasure of Cider.
Shindo was about to get annoyed, but he feels how Izuku started cuddle against his chest, as he wanted to stay as close as possible to the two boys he's secretly in love with.
Izuku is just so happy to have both of them for him that even he forgets about the movies to enjoy the warm and softness of Shindo and Cider.
The tension between them also goes away pretty quick, as in the end they just want their beloved Izuku to be happy.
...
P.S: Cider also shaved a side of his head for match hairstyles with Izuku. Yes these boys are that silly for their brocoli.
HELP THIS IS SO FUNNYKJSDJKSDKJ I think this might be the second throuple I get since Kirishhima, Kaminari and Sero, so shoutout to you!!!
I love the idea of them "fighting" for Izuku's attention, they are so committed to surpassing the other that they don't even realize Izuku has been setting up dates with both of them in the hopes they will get along better and it just turns that they are months into this dynamic and don't know they are all kind of dating kjdfjkfd
It's so funny imagining all 3 of them with the fuckass lesbian haircut just to match Izuku and make him feel a little better <33
Tenko tried to copy that beautiful shot of Nine's hair dramatically blowing at the wind.
But it didn't work.
Sorry Tenko but your hair looks like the mop that nobody replaced in more than five years.
You could never compare to Nine's ethereal beauty 🤍🌩
Greek gods energy 🌩
Whoever decided it was a good idea to gift us with the image of AFO and Nine showing their perfect bodies, thanks to that person 🙏
Yoichi is trying to keep his brother warm.
A soft Valentine's gift for them <3 Thank you @nyc3 for the most excellent mental image!
Full image under the cut, mind the 🍑
Can we talk about the way Katsuki looks at Izuku in OFFICIAL art?
He's so big 🥲
Speaking seriously, he seem to be a big guy in general not just tall. These panels in particular always give me the feeling he's a very big guy despite not having a physical enhancer quirk.
Also he already got nice muscles despite being homeless (?)
And his shoulders are wide 🤭
Our boy was working on those streets.
Imagine how much bigger he would be if he had a proper home and family growing up.
Ok it’s just the camera angle making him that way but according to that wiki site he’s 6 ft 2 so he also tall
not afo tall……but still
he ate all his fruits and veggies growing up 😌
…despite the fact he probably had no one take care of him growing up, poor nine baby 😔
just found this photo and I just think he look silly
Cider House gang leader.
How a minor villain with a few chapters of screen time have such an awesome design and power?
I really need more Cider content now 🌊🩵
But Chisaki needs a maternal figure in his life as well... and considering I ship OverHawks very hard is funny imagine Nagant reaction when she see his successor and the yakuza she rescued together. She would be like "The world sure is tiny".
Outside of that she taking care of Kai shows how her primary instincs of being a protective figure are still there, which could also extent to other characters.
...
Kind of funny how Shoto with a double effect quirk is seen as some kind of miracle and god among mens, yet when Midoriya starts unlocking quirks every month people is like "oh yeah whatever".
I think that's just Horikoshi making everyone act like an idiot only for the reveal of OFA being a thing look like a big surprise, but that only makes the characters seem stupid. And there's this recurrent joke among the fandom of how the photographer dude from S4 discovered Midoriya secret after spend a few hours with him, but his friends just give his power for granted.
Cider is way smarter than them. He would notice something isn't very normal about a person with so many powers, but that also would fascinate him and what to know more, because it is a cool thing to have.
His line "I'm a man who lives for the thrill" lives in my mind now. Rent free. He is a bold but smart man.
I was wondering...what it he goes to steal smth in UA? Not sure on what he could steal but hey why not? That would be a huge blow to their egos.
Plot twist. Izumi beats him first and she is the one to invade UA and stole SMTH - it was crucial for her plans- BK tried to downplayed so hard but hates how everyone is impressed.
No idea of what he would steal, but if he and Izu converge the same day with the same plan of steal some shit and they're like "wtf are you doing here?".
They almost start fighting but then Bakugou appears and tries to capture them screaming "Die!" as usual, but then Izu and Cider join forces and humilliate BK in public in the U.A grounds. A hard hit for his ego.
That would be also a moment for fall into a spiral of love and horniness for our thiefs.
If I had a nickel for everytime Johnny Yong Bosch voiced a badass white haired character with big pecs who ends being experimented in a tube I will have two nickels...
And I wish it happens more often
This is such a specific niche of characters I love.