Transmatsu headcanon: Karamatsu disappears for a long time and none of the brothers notice. But one day, they find a girl who looks a hell of a lot like them in their house.
It’s Karamatsu. Karamatsu completely transitioned without any of her brothers noticing.
At first, none of them believe it, so they tease and bully her saying it’s just Karamatsu crossdressing as a ploy to get attention. But then Karamatsu starts crying, breaking down and bawling and the rest are just “fuck, we messed u p.” Matsumama comes in and yells at all of them while consoling her daughter (which she and Matsupapa are so happy about because they always wanted a girl) and now the brothers feel just awful.
Karamatsu leaves first to fix her makeup and visit Chibita at his oden stand (to cheer herself up) and Matsumama just hisses at her sons “you better fix this.”
Chibita nearly has a heart attack because while Karamatsu confided in him from time to time about transitioning in passing, he never fully registered what it would mean until seeing Karamatsu now. Chibita is so flustered he barely knows what to do, but Karamatsu starts sobbing about how jerky her brothers are and Chibita gives her everything on the house while telling her she doesn’t need her good-for-nothing brothers anyway.
Cue the good-for-nothing brothers showing up. Jyuushimatsu literally picks Karamatsu up, while Osomatsu downs the rest of her beer and Ichimatsu finishes her leftover oden, and they take her back to the house. In the living room, Jyuushi puts Karamatsu down so she can see that there’s an assortment of food and a cake. Karamatsu is confused an she turns to her brothers as they all bow and say “sorry for being assholes.”
They’re all on good terms now, but Karamatsu is officially 100% impossible to ignore by any of the brothers. Every time she goes out, one or more of them insists on accompanying her (eventually they develop a rotation system to escort her, but Ichimatsu somehow always ends up going with her the most); the only exception being when Karamatsu goes out shopping with Totoko (Ososmatsu will still try to weasel his way into joining them, but Totoko gut punches him and that the end of that).
Choromatsu spoils her the most, mostly because he doesn’t now how to deal with women and showering them with gifts is all he knows to do, picking up random things Karamatsu likes when he goes shopping.
The brothers start getting real suspicious of Karamatsu going off to Chibita’s stand alone, and one day Karamatsu comes home with a bouquet of flowers and the brothers are like “where did you get that??” Karamatsu has this cute pink blush on her face and says “Chibita found some flowers on the roadside and he gave them to me!” All the brothers know that those flowers are too good to have been found on the road and they’re wrapped all nicely too, so they face-palm and curse that Kara has and always will be gullible. (They totally storm Chibita’s oden stand later and threaten him not to mess with their sister, Todomatsu is unsurprisingly the scariest)
Iyami had no idea Karamatsu had transitioned, so when he first sees her, he hits on her like nobody’s business. Too bad she happened to be out with Jyuushimatsu, and he proceeds to beat Iyami within an inch of his life with a bat.
Karamatsu is still painful as always, posing dramatically to fall into men’s arms and dressing up like a “cool” yankii to hit on girls, spouting awful lines that make everyone cringe.
Just, please, someone, anyone, give me this au…give me trans Kara in all the cute dresses and outfits they deserve, receiving all the love they can get from everybody…. ;~;