A brief description of the manga Maou No Ore Ga Dorei Elf Wo Yome Ni Shitanda Ga, Dou Medereba Ii?:
People think of Zagan as an evil magician and therefore fear him. Socially awkward and sharp on the tongue, he spends his days studying magic and beating up any violators of his territory. One day he was invited to an underground auction, where he met an elf girl slave of incomparable beauty called Nephie. Having fallen in love with her at first sight, Zagan spent all his wealth to buy her. Being a terrible conversationalist, he can’t get along with her.
Thus began the adventures of a magician who does not know how to express his love and an elf – a girl. She seeks to repay her master, but has no idea how to do it…
It’s not an isekai, and there’s no harem (Ch. 68), but there is an OP Mc.
The unsociable magician Zagan sees one of the rare elves at a slave auction he attends with his friend. He falls in love with her, buys her, and undergoes significant character development thanks to her.
Due to his strength, he is appointed successor to one of the thirteen demon lords. These are powerful sorcerers who possess auf inheritable sigil. Why they are called demon lords becomes clear as the story progresses.
This is cloyingly sweet and even a little cringe, but you probably won’t mind. Charming romance with an anti-hero protagonist. MC is OP, and good thing, because literally everyone with power is coming for his head. All MC can think about, though, is cherishing his new cute elf slave, who is falling for him just as hard. So nice, I read it twice. Strong recommend!
Has or is a spinoff manga, can’t remember which.
Very good 11/10
easy 9/10
ANIME!!
Dude I am a cold, cynical, emotionless person, but all I want is to buy her, so I can set her free!
slave manga, immediate 0/5
It’s soul bleach, it goes far beyond palate cleanser, it’s soul beach.
the guy looks AWFULLY a lot like lucifer from obey me..identical even. 
unique plot and story line. romantic and machiavellian.
Not to lie, it was hard to read the first chapters, but unlike in most of those edgefests character growth and feels here are quite right, so I recommend
Is this animated? Bcuz I hope so
I was seriously skeptical but I really, really enjoyed reading. The characters are sweet, funny, serious, annoying, naive and so much fun getting to know. So seriously looking forward to where this story goes from here.