Read manga: Shinmai Maou No Keiyakusha

manga
Summary:

"Hey, you said you wanted a sister, right?" First year highschool student, Toujo Basara, was suddenly asked by his father and fell into a state of panic. On top of that, the eccentric father told him 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 the newbie Demon Lord and a succubus!? Basara was almost entered 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 situation 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!

Chapters (46)
Aug 25, 2019
Chapter 0 : Prologue
Aug 25, 2019
Chapter 1 : How To Conquer Your Step-Sister
Aug 25, 2019
Chapter 2 : Demon Lord And Hero
Aug 25, 2019
Chapter 3 : The First Master-Retainer Contract
Aug 25, 2019
Chapter 4 : Between Reunion And Trust
Aug 25, 2019
Chapter 5 : In Between Reunion And Trust (Part 2)
Aug 25, 2019
Chapter 6 : Enemies And Allies
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Chapter 7 : Until You Are No Longer In Sorrow (Part 1)
Aug 25, 2019
Chapter 8 : Until You Are No Longer In Sorrow (Part 2)
Aug 25, 2019
Chapter 9 : Until You Are No Longer In Sorrow (Part 3)
Aug 25, 2019
Chapter 10 : Things I Want To Protect
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Chapter 11 : Unrivalled Morning Sister Demon Lord
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Chapter 12 : Hold Onto Your Growing Feelings
Aug 25, 2019
Chapter 13 : The Hostility Directed At Us
Aug 25, 2019
Chapter 14 : The Goal Of A Master-Retainer Relationship And Trust
Aug 25, 2019
Chapter 15 : Gaze At The Past That Won T Disappear
Aug 25, 2019
Chapter 16 : Their Fates Cross
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Chapter 17 : Before One S Resolve, The Things One Wants To Protect
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Chapter 18 : Put Your Resolve On The Blade
Aug 25, 2019
Chapter 19
Aug 25, 2019
Vol.5 Chapter 20 : Time For A Reckoning
Aug 25, 2019
Chapter 21 : What A Man Belives In
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Chapter 22
Aug 25, 2019
Chapter 23 : The Sexy Lil Succubus Rampage
Aug 25, 2019
Chapter 24 : The Sexy Lil Succubus Rampage Part 2
Aug 25, 2019
Chapter 25 : The Second Servant-Master Contract
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Chapter 26 : The Ups And Downs Of A Wavering Pact
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Chapter 26.5 : An Average Day In The Life Of Toujou Basara
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Chapter 27 : Betrayal, And Then
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Chapter 28 : Betrayal And Connections
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Chapter 28.5 : The Testament Of Sister New Devil
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Chapter 29 : Parting And Reunion
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Chapter 30.5 : Maria The Graphic Novelist
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Chapter 31: Vol.8 Pact 31: Basara Vs Maria
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Chapter 32: Vol.8 Pact 32: Master
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Chapter 33: Vol.8 Pact 33: Everything War For This Moment
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Chapter 34: Vol.8 Pact 34: The Demon Sword Gramr
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Chapter 35-P35: Vol.8 Part 35: The Results Of The Decision
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Chapter 35.5: Vol.8 Pact 35.5: Behind The False Smile
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Chapter 36: Vol.9 Pact 36: Mio S Awakening
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Chapter 37: Vol.9 Pact 37: Runic Sword
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Chapter 38: Vol.9 Pact 38: A Score Settled
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Chapter 39: Vol.9 Pact 39: Return
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Chapter 39.5: Vol.9 Pact 39.5: [Side Story] Go With Maria
Aug 25, 2019
Vol.9 Last Pact
Aug 25, 2019
Vol.9 Pact After: The Toujou Family: Afterword