The Testament of Sister New Devil

Toujou Basara is an ordinary high school student whose father unexpectedly remarries and then leaves the country, leaving Basara with two new step-sisters, Mio and Maria. Unbeknownst to him, they’re no ordinary girls-Mio is the next Demon Lord, and Maria is a succubus. When they try to force him into servitude, Basara accidentally turns the tables, forming a reverse contract that makes him Mio’s master instead. Now caught in a whirlwind of awkward and risqué situations, Basara must also protect Mio from relentless enemies-both demons and heroes-who seek her life.