Basara Toujou has a difficult existence. He is the older stepbrother of two demonic sisters, Mio and Maria Naruse, whom he shields against entitled demons seeking Mio's power. Furthermore, escalating political tensions inside the demon world make his work even more difficult. When a messenger arrives with a summons to the demon world for Mio, she and her pals travel despite the danger. Basara will have to become stronger via romantic pleasure now that she is on the enemy's soil in order to perform the impossible and defend everyone.