The Testament of Sister New Devil

Basara Toujou’s first day with a new family gets off to an awkward start—literally—when he runs into one of his new stepsisters in the bathroom. Soon after, his father introduces two girls as his new siblings: Mio Naruse, a curvy redhead, and Maria, a petite silver-haired girl. Basara tries to adjust, but the “ordinary” home life doesn’t last long.

Mio and Maria reveal their true identities as demons: Mio is the former Demon Lord’s only daughter, and Maria is her succubus attendant. Cornered into exposing his own past as a member of the Heroes—traditional enemies of demonkind—Basara chooses to protect them instead, forming a master–servant contract with Mio to keep her under his watch. With Heroes scrutinizing his actions and hostile demons closing in, Basara fights to keep his new family safe, even as a personal secret continues to shadow him.