The trauma was recently resolved after the ex-boyfriend was arrested for stalking but the side effect is that the FMC has lost her sexual desire while the MC still unable to get rid of his masochistic fatish.
So the
FMC devises a new plan,
she wants to take over the role of bullying the MC from the three girls. She enlists their cooperation for one-time "
fivesome" asking them to teach her the ropes.
In the latest
chapter 95,
Chisaki and Kanako (especially Chisaki) achieve their own goal of actual intercourse with the MC. Meanwhile,
Tsubami who prefers using toys chooses to preserve her virginity for a future boyfriend. So, she
engages in the kind of rubbing and grinding she is accustomed to.
IMHO, It might end with everyone remaining good friends at the university, with the
FMC taking the
MC a slave under her wing instead of those three girls as she planned. The MC will move out next week so he'll not stay close with
Chisaki anymore.
A harem ending seems unlikely, as the three girls would probably defer to the FMC out of consideration. Or I'd say it's up to the FMC's decision whether to share the MC. We can notice that
Tsubami wants to keep her virginity means she won't end up with the
MC.
Kanako is a lesbian so she's not problem at all.
The only person who truly has the hardest time will be Chisaki because she has liked the MC ever since before the shirt-stealing incident though she told Kanako that she was going to give up on MC. Sad for her.
Deep down, she is in love with the MC since she saw his face clearly and thought he's cute, but because it is an unrequited love, she feels absolutely no sexual desire for other men no matter how she tried. It’s likely the MC was interested in her as well but the incident twisted their relationship into what it is today.
Perhaps the author want to help resolve Chisaki's psychological hang-up by having her successfully has sexual intercourse with the MC that she's longed for in this chapter 95.
Personally, I find this aspect quite pitiful. Otherwise, a story about
Chisaki and the
MC falling in love could easily stand on its own as a
rom-com (a gyaru and a nerd) or a "what-if" story.
References : Ueno-kun Has Been Developed (Ueno-kun wa Kaihatsuzumi)
https://yanmaga.jp/viewer/comics/上野くんは開発済み/daedcb18f48fd613d2a1cea3d7ae02a2?cid=06A0000000001022356S and
https://mangadex.org/title/09807595-57cf-47e8-bd46-748ea5170b77/ueno-kun-wa-kaihatsuzumi