Oops forgot the version can be either 1 or 2. Also switched roles AU if it's feasible. What monster would Rosie even be.
Ok your ask sent me down a rabbit hole and I committed to a complete role swap for this shitpost. Full blown AU.
Rosie Wensley-Banner [the Scarlet Starlet] is a horny healing bard from a long line of English witches in service of the church, so Kuro in this role...is the horny poison bard from a long line of cursed chemists serving as the royal apothecary. The Mahogany Miasma, civilian name Humbert Blackbane [Lolita reference like Rosie's title, and an English plague]. Nickname Umber, or Bert if you want to commit sudoku. Still the same hobo-military sense of fashion also. Rosie's 60s type shit translated to Beatles Sgt Pepper undertones.
Kuro/Okami is an inugami-possessed oni, who wreaked havoc near the end of the warring states era and sought only to have children and a loving pack. Rosie in this role...is the plucky nekomata, Tsubakineko [Literally, "camellia cat".] Nickname Cammie. More or less a gentle catgirl with a mischievous streak, she was denied any human friends or partners and other yokai considered her too weak and stupid to join forces. In the modern era, catgirls are highly coveted so she has to fight people off, which gives the impression that she's a monster to target.
TL;DR "Toxic" by Britney Spears x "Toxic Love" from Ferngully 😭
It would be far more wholesome this way though. Rosie is just a pure soul in any incarnation so she would probably get folded into the heroes' group immediately because she's lonely. Galahad and Umber constantly scuffle over muh catgirl gf. Soraya still has a gay crush and she still hates spooky bastard, double so now that Cammie's in the picture and warming up to Umber. Alicia is 200% done from the get-go but is very protective of Cammie.
The wedding isn't secret and they continue life normally. If the roles are swapped here then this might be the AU where Kanna is the only one with powers.
Almost all problems in Sins of the Father stem from the father, so that's unchanged. He's still fairly unhinged, only now the mind poison is literal rather than metaphorical. Midas type beat. Except the hero team stays in touch, so now the girls have aunts and an uncle to confide in. They gon fuckin need it too.