Dude has an astronomycal inferior complex caused by both his "perfect" (yes emphasis on that) and any girl who uses him as a way to talk with his brother of course including his crush which is also his childhood friend. Now, despite that he still thinks he has a chance to win over his crush by making his brother's crush and his brother getting together (which is impossible for reasons I will cover later).

The indisputed and almighty "perfect" brother, hoo boi how do I start with this complete mess of a character, he is supposed to be written as a character you are supposed to hate... right? (Don't worry you will until ch.69 but I'll talk later about that). Now he is the reason our MC is dense and annoyingly distrustful with anything Kano does during the beggining, he is also a childhood friend of MC's crush and the latter's actual crush (despite him not really giving a single f*ck about her, just keeping her around to mess with the MC). He has a massive crush on Kano who literally says "nope" every time he confesses. He acts like a complete as*hole torwards the MC if he hears "Yuito" and "Kano" in the same sentence, he also looks down the MC constantly and until ch.68 where Kano literally tells him without any rondabouts that she loves the MC his ego breaks and in ch.69 we get his PoV on things... and this chapter is hilarious, the author wanted to feel sympathy for him but it had the opposite effect, if anything that chapter itself is pure unadultered comedy, why? Well we get to know why he looks down the MC and... is because during their childhood, both him and the MC saw Kano being bullied and while he being the "perfect one" he lacked the balls to help Kano, unlike the MC who jumped and despite getting beaten, he protected Kano (which ignited Kano's love torwards the MC), Since then the "perfect" brother started to look down the MC just to quoted by the actual character, "protect his fragile ego"... which ends up breaking apart after Kano's words, what makes this even funnier is that the dumbass started to say "I wish I were Yuito" I was like "bruh" when I read that, and after that he ends up getting a cold haha. The best part of that are the author's notes after all that justifying Ayato's behavior through the novel at the end of that chapter, pure comedy.

Yuito's unrequited crush and the one having an unrequited crush on Ayato. This character is garbage, she only exists to make the MC suffer and she is the main reason this novel dragged this long, she like any other girls who is not named Yuuki Kano, has a crush on Ayato's "perfection" (and yes, that's all her depth), now why is this mess of a girl the most annoying character in the novel? Simple, because she uses Yuito as a ladder to get to talk to Ayato (mind to add that the 4 main characters are childhood friends so she has no reason to trample the Yuito like that), Yuito ends up rejecting or avoiding any advances Kano tries with him as a result of the lack of trust and inferiority complex and this is all her character is, an addon to Ayato and the device to stretch this mess of a novel.

The undisputed yandere girl, when introduced she acts like the typical teasing gal with Yuito, but actually she has a crush on him since childhood after the shrine incident where she was being bullied where Yuito protected her, now, why is she the only saving grace? Is it because she is the only one that loves Yuito? Maybe, but the main reason is because she is aware of the main issues regarding our main cast, she know Yuito is a better guy than he gives himself credit for, also she know that Yuito has a crush on Suzuno (her own sister) but unlike Ayato who acts like a whiny b*tch, she doesn't have any hostility against Suzuno, she knows that she is "Suzuno's big reliable sister" first and foremost meaning that she doesn't look down at her, she helps her when she needs help and she spends time with her. Her behavior torwards Ayato is simple, while she doesn't hate Ayato, in fact she considers him a friend, she knows that he is a douchebag and that he has no chance in hell to even date her after all, despite he being a coward, has the audacity to look down the one she loves. Regarding her behavior with Yuito, she is head over heels with him, at the point of going full yandere, now, while she goes yandere mode, she isn't actually a yandere, she does things line erasing any other female contact in her phone, wiretap his browser history and install a gps on his phone, she barely even uses those things as she actually puts a whole lot of effort on winning him over (unfortunately even to this day, he still has a crush on Suzuno despite everything has happened, even Kano's confession which is the main reason people really hate this MC at times, myself included). As I stated before, any progress this novel should had made, is halted because the existence of Suzuno of course that includes Kano's advances, Kano's confession (ch. 30++), Ayato's breakdown (ch.68) and even the trip to kyoto.

Kano (Older Sis) persistently hangs out with him and drags him around. The MC thinks of it as "friends hanging out", when Kano is clearly taking him out on dates (Hotel room with 1 bed, Vacation, etc.).

Kano takes the MC's phone and deletes all female contacts, which she never mentions why (The MC is SUPER dense for not knowing why she did this LMFAO). While also installing an invisible app that tracks what he searches up, his location, etc. All of which is pretty standard Yandere 101.