Looks like this
might have links to the entire work.
Sumaru is a school playboy (and throughout the narration, a single-minded asshole who considers being forceful "if he can't help it"), and now that parents aren't home, now's his chance to bang someone. On his school week he meets:
- Saki (2nd year 16-17?, noted to look younger), a next-door childhood friend who lives with him because Subaru can't cook or clean, with a chronic case of Thousand-Yard Stare whenever Subaru isn't paying attention.
- Maika, his kohai (15-16?) who is traumatized from bullying, with growing attachment issues because Subaru protected her one time.
- Yuumi, his homeroom teacher, who's openly thirsty for him and tries to find and excuse to leave him after class or visit his house.
The week is a rotation of morning routine, class dialogue and afterschool hangout, with explicit porn throughout depending on your answers. The route is effectively who've you've had more, with some times unavoidable.
Half-way it becomes apparent that all three are way overly affectionate, and whoever's route you're on isn't safe either. At the ending any number of the cast are killed off in graphic fashion. There's a secret ending that isn't a happy one either.
Pure porn, minimum plot, cut it. TroperWall / WikiMagic Cleanup

The flag here for YandereILoveYouSoIWantToKillYou was sent with the rationale