The Testament of Sister New Devil Season 1

The Testament of Sister New Devil (新妹魔王の 契約者 スタメント) is a anime series based on the light novel series by Tetsuto Uesu with illustrations by Nekosuke Ōkuma. The story centers around Basara Tōjō a Year 1 high school student who wanted two little sisters. One day he 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!?