Isekai Elf no Dorei-chan is what you would call a borderline hentai, but never quite gets there as all you ever see are some nipples, everything else is you're typical censored out the wazoo, if you've ever read "What Happens Inside the Dungeon" the censorship and borderline hentainess is almost exactly like that. It should be noted that this manga got me through a period of rather annoying illness, so perhaps my view is coloured in an overly positive manner, but regardless I love Isekai Elf no Dorei-chan so much it's now one of my all-time favourites and truly wish for an anime adaption, not tomention more of this manga itself.

Isekai Elf no Dorei-chan starts off with the Master (yes that's his name as far as we know) and the two slaves (prepare to be cancelled) Inumimi Chan (a Lycanthrope, basically a dog girl) and Elf Chan (she's just an elf, hard as her name makes it to tell) both of whom are absolutely adorable and cute beyond words! They're also the main characters.
Now I see that's peaked you're curiosity, the slaves as main characters? Is 'Master' bad? What's the deal? Well, now you've started thinking there's more to it than there is, so lets be clear as to what Isekai Elf no Dorei-chan is.
Isekai Elf no Dorei-chan is a comedic parody of the Isekai dungeon trope with plenty of pervyness and adorably cute girls and a very basic story designed only to support those main two things: comedy and the ecchi part and as a result it excels in that department.
Despite calling the story basic I did actually kind of find myself engrossed in the story, so errr, yeah, take that how you well.

I would also be remiss to mention how good of a job the art does of capturing the cuteness of the characters it's truly beautiful for a manga that only got 4 volumes it's feels more valuable than that, suffice to say the art helps a lot with keeping everything together.