About the blackmail... I don't think it's right to dismiss the basis on which a story was built, but I do think that's what the author wants me to do. The idea for this manga looks like it started with Takamine as an overwhelming threat (at least I didn't think that scene was funny), but because it had to be a romcom, we are gradually being shown kinder sides of her so that she can seem more likeable, leaning more to a "lovable dominant" than a "supernatural sociopath". And at this point, I'm already invested enough to keep going.
But I've always thought that this manga would be a lot cooler if Shirota was a super smart Shirogane-type guy that was constantly searching for a way to rid himself from the threat that Takamine hangs over him while managing school, family and her demands (maybe it's my love for PMMM and time travel, I dunno), and the ultimate lesson was that, in an attempt to esnare the guy she liked to her with this extreme method, she ended up creating an enemy instead. But since he's a doorknob, the story can't go that route once it's started. Kinda like if Hiiragi changed their mind right after a few chapters.
All of this is just my speculation and viewpoints. I've made peace with reading this as a romcom. But it could've been a lot better IMO.
