Shinmai Maou no Keiyakusha


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“Hey, you said you wanted a little sister, right?”

First year highschool student, Toujo Basara, was suddenly asked this question by his father, and he fell into a state of panic. On top of that, the eccentric father told him that he will be getting remarried. He then departed overseas after bringing Basara two beautiful step-sisters.

But Mio and Maria’s true forms are actually a newbie Demon Lord and a succubus!? Basara was almost forced into a master and servant contract with Mio, but a “reversed” contract was formed by mistake, and Basara is now the master!? Moreover, Basara is being hit by ecchi situations one after another due to the contract, but Mio’s life is being pursued by other demon tribes and hero tribes!!

The most powerful contractor’s desire action drama begins!

Associated Names
One entry per line
Shinmai Maou no Testament
The Testament of Sister New Devil
Related Series
A Wife’s Cry (1)
Recommendation Lists
  1. Ero Stuff
  2. s*x List to download later
  3. Villain/Harem/R18
  4. My List Harem LN/WN (MC Polygamy) V2
  5. Personal Recommendations

Latest Release

Date Group Release
12/05/18 The MasterPaster’s... v9c1
11/26/18 The MasterPaster’s... v9 prologue
01/21/16 Baka-Tsuki v9 illustrations
10/08/18 zxzxzx v8 afterword
10/08/18 zxzxzx v8c3
08/22/18 zxzxzx v8c2
08/03/18 zxzxzx v8c1
06/11/15 Baka-Tsuki v8 illustrations
11/03/17 zxzxzx v7 afterword
11/03/17 zxzxzx v7 epilogue
10/23/17 zxzxzx v7c4
05/05/17 zxzxzx v7c3
10/11/16 zxzxzx v7c2
06/24/16 Baka-Tsuki v7c1
01/18/16 Baka-Tsuki v7 prologue part4
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9 Reviews sorted by

nobelvampire1071 rated it
May 12, 2016
Status: --
Well if you like shounen and typical MC which is the type to never give up and protect all etc this is for you. MC is strong but not overpowered.

Also there are lot of scenes bordering on hentai. Each girl has their own separate arc where he saves them.


In general this is a typical shounen slice of life harem anime with your average MC. Well a special point about MC is he is not afraid of killing.

He killed zelrog or some1 I forgot the name by giving him to some other guy to torture and then came to see himself while the other guy killed him. That was fun

Its fun to read.
11 Likes · Like Permalink | Report
cpkdillon rated it
July 5, 2017
Status: v9 illustrations
This is a great fan service/action novel and continues to improve as time goes on. But if your not interested in fan service (even if its the most well done I have read) then this is obviously not for you. There is also a good anime adaption.
7 Likes · Like Permalink | Report
Yellowgoodboat rated it
February 7, 2021
Status: Completed
Okay, I would like to give my honest opinion on this light novel. Sooooo, it's for horny people only. Yea, that basically sums it up. If I were to go into more detail, volume one -three is pretty good. The rest of the story is basically just some protagonist with a hero complex but without any actual strength, saving girls and only surviving because of plot armor. It is kind of s*upid actually. And also, having a god in your harem??? Implausible, but ok. And also, the fight scenes are... more>> just laughable, because of the sad descriptions and his weak overall power. I had a frustrating time reading this novel, because of the fact that MC is just too headstrong or too absorbed in his 'hero complex' moments, saying all those cringy lines without any strength to back it up. <<less
6 Likes · Like Permalink | Report
VinzeDiesel rated it
July 8, 2020
Status: --
Well.. Technically the best Adult Light Novel that doesn't just cover boobies, but also has a great plot.

I've never found Light Novel such as this. For the main character who doesn't simply have a s*x with everyone around without reason, Toujou Basara is forced by the circumstances to do that part. He isn't s*x maniac like every adult type of genre, and he is responsible towards them and wanted to protect them even if it costs his life. No other main character like this as far as I know from... more>> the start.

So far the greatest light Novel I've ever read <<less
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stanljpierre rated it
June 11, 2022
Status: v12
One of the better harem JP LN's I've read up until now. Plot is fairly mediocre, but it isn't bad. My feelings about the MC are quite split, but at the very least he's likeable. Moreover, he isn't like the typical dense and timid JP protagonist who're scared to be intimate with his women. That's one plus I have to give to this novel. The H scenes were very well written, especially when it came to them all finally crossing the final barrier of their relationship.

Not much to really complain... more>> about really, though fights weren't really to my liking. Felt like the MC was just barely surviving on several occasions and constantly fighting uphill battles that he has to give his everything to win and if not for plot armor he'd have died many times over.

Anyhow, this was an enjoyable read. Won't lose much by giving it a chance, although I'd try not reading this in the company of other people. <<less
3 Likes · Like Permalink | Report
bushwhacker2k rated it
December 14, 2018
Status: v8c2
Can be basically split into three parts:

1: Combat

2: Story

... more>> 3: Ecchi

Combat feels pretty boring to me, basically every fight goes the same way, the good guys have some epic struggle and barely win or barely survive. Every time. If there's a tournament where 4 losses means your team loses, they will absolutely lose 3 times. I can't feel any consistent power level for anyone, because it seems to work out the same way for every fight. (They also throw around power ranking terms like B, A and S rank, but the characters start the story on the fringe of A rank anyway, making the ranking mostly pointless) The protag was supposed to have been some kind of 'genius', but he gets kicked around in basically every fight. The Story is annoying to me. It feels like nearly every person they meet is condescending as hell, but you're ultimately supposed to feel gratitude and/or sympathy towards them. Like the combat segment, there are few exceptions, it's super annoying and I can't find myself liking characters outside the harem.

Ecchi is really well done, very enjoyable. Not many novels have done it nearly this well. This is what people should read this for.

I gave it a 4/5, but if you split it into Ecchi and Combat/Story, it's 5/5 and 1-2/5. <<less
3 Likes · Like Permalink | Report
mechafanboy rated it
November 1, 2016
Status: v3
Fanservicey to the point that the novel literally spends a large portion of pages (probably 20% at least per volume) talking about fanservicey nonsense.

There's an underlying plot, but frankly it's annoying wading through the all the nonsensical bs to get to the plot. The rating might be slightly harsh but that's primarily because I personally feel annoyed with how slow the plot progresses not due to additional character building but rather needless sexual gratification.

We get it, he's surrounded by pretty girls and most of them want to be his s*aves.... more>> Stop writing a paragraph about it every chapter and maybe the novel's pacing wouldn't be completely horrible. <<less
3 Likes · Like Permalink | Report
PhantomLily rated it
June 24, 2016
Status: v7c1
Fantastic novel and plot. Always loved the Angel, Hero, and Demon kind of thing. Nice action between the MC and his girls too ;)
3 Likes · Like Permalink | Report
wargrelet rated it
August 23, 2018
Status: v8c1
well a typical novel story didn't like the plot much only read due to damn hot girls !!!hurrayy!!! To the author and illustrator for that

story was okay but battle parts buzzes me off, battle didn't seemed like a battle they seemed like way to promote

erot*c power boost and their school life seemed more realistic than battle part

well anyway I like the protagonist Basara, Mio was very hot girl, Yuuki character was understandable (who would like their childhood crush to be stolen), Kurumi seemed like forced to harem, and Zest... more>> is most adorable of the girls with Chisato being the sexiest, Maria was the misfit of the bunch

so what you see in story is a plot due to demon lord position just like in politics of our world

a s*upid hero clan (and why I call them s*upid is because the banishing incident where elder bunch of hero clan didn't even try to use any magic to stop the culprit I mean it is the origin of heroes and they don't even have a powerful guy stationed there in case anything happened, seemed foolish to me)

Author did a fine work for their school and normal life but failed at making the battle seem real or it could have been great (i seriously recommend author to work on making battle feel real) reading the battle the made me feel like I was swallow something that could have been a fine piece of work if some proper ingridients were added

(so for god sake make monologue and dialogue during battle realistic)

so I gave it one star for school life and normal life and one for the girls and if the battle were good I would have given it two more stars (and don't expect a total of five stars from me I mean the protagonist has a harem and he should be kicked there by every girl once for having a harem like how mio kicked in beginning and only once by every girl except Chisato because I don't hate the guy it just soothes my soul that at least he suffered once from each girl except Chisato it just doesn't suit her to do that) <<less
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