The Testament of Sister New Devil BURST

新妹魔王の契約者 BURST

After two demon girls, Maria the succubus and Mio the demoness, force Basara into a contract that makes him their master, the trio form a complicated master-servant relationship. Basara is the last descendant of a demon-fighting hero clan, but as master of two demon girls, he finds himself defending them instead of fighting them. (Source: Funimation)