This series is not completely translated. Japanese Title : 新妹魔王の契約者〈テスタメント〉 Author : Uesu Tetsuto (Story), Ookuma Nekosuke (Art) Genre : Action, Ecchi, Fantasy, Romance, Harem, Supernatural Published : Oct 1, 2012 - Apr 1, 2018 Volumes : 12 Chapters : 58 MAL Baka Updates Novel Updates Synopsis : "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 M
Harem Endings are Happy Endings