The Testament of Sister New Devil

Synopsis

Basara Toujou's initial encounter with his new stepsister takes a sour turn in a restroom. His life is upended when his father brings home two stunning young women to join the family: the Naruse sisters, consisting of the voluptuous redhead Mio and the petite silver-haired Maria. Their human guise quickly dissolves to reveal their true nature as demons. Mio is the only daughter of a former Demon Lord, while Maria serves as her devoted succubus companion. This shocking discovery also unveils Basara's own lineage as a member of the Hero clan, the ancient adversaries of demonkind. Despite this historic rivalry, Basara feels an undeniable pull toward his new family. Opting to protect rather than fight, he forms a master-servant pact with Mio, pledging to guard her with his unique powers. Now, Basara faces the arduous challenge of shielding his new relatives from the gaze of the Heroes and the hostility of other demons, all while harboring a troubling personal secret.

Background

Shinmai Maou no Testament adapts the first 3 volumes of Tetsuto Uesu's light novel series of the same title.