Plot Bullies uses MC's phone to lure and rape MC's childhood friend/crush. When MC arrives to stab the bullies with knife, the demon of lust appears and offers him a contract to take "proper revenge". MC will get teleportation skill and help from demon, to mindbreak and NTR the bullies, just like they raped his childhood friend. Review Good: * edgy story of revenge. demon plans a strategy using psychological techniques and MC executes that strategy. He does question his methods at times, but fortunately, he remembers the past and just commits to his mission. * We do have lots of [short] erotic scenes. They are kinda fucked upand dark at times, but also happy (?) like a regular harem at other times (stockholm syndrome?).
* The demon girl is written as this bright and bubbly cousin which contrasts hard against the dark setting. She basically hard carries this manga.
* perfect title. NTRevenge describes this series perfectly, and you know exactly what you are getting into.

Bad:
* Garbage Art: the manga looked like a rough draft/sketch of outlines and almost no shading. Erotica with bad art are just sad.
* Slow pacing and Irrelevant filler: The investigation of kidnapping by cops is distracting and drags the pacing. There's also a lot of scenes which try to show how the girls are competing with each other for MC, but IMO, they just don't belong in a dark story like this.

Overall
It is very hard to recommend an erotica with bad art. Still, if you are here for NTR + revenge, then you are at the right place. Every story has its target audience and this is an average / good-enough series for that audience.