Shinmai Maou no Keiyakusha Wiki
Shinmai Maou no Testament I
Volume I.png
Basara Toujou and Mio Naruse
Kana 新妹魔王の契約者I
Romaji Shin Imōto Maō no Keiyakusha I
Air/Release Date September 29, 2012
ISBN ISBN 978-4-04-100495-1
Pages 299
Next Shinmai Maou no Testament II

Volume I is the first Light Novel of Shinmai Maou no Keiyakusha.


"Hey, you said you wanted a little sister, right?" First-year high school 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!


  • Prologue - The Day He Got a Little Sister
  • Chapter 1 - The Way to Conquer Your Little Stepsister
  • Chapter 2 - First Master and Servant Contract
  • Chapter 3 - At the Threshold of Trust and Reunion
  • Chapter 4 - Until Your Sadness Becomes Nil
  • Epilogue - What He Wants to Protect


Main Characters Returning Characters New Characters Antagonists

Novel Illustration