Toujou Basara continues his relentless efforts to protect his demon step-sisters Naruse Mio and Naruse Maria from the demons who seek to claim Mio's overwhelming power, all while the political unrest in the demon realm grows more intense. When a messenger calls Mio to the demon world, she sets out on this dangerous journey alongside her allies. Left stranded in enemy territory, Basara must use the power of erotic pleasure to enhance his strength, striving to accomplish the seemingly impossible goal of keeping everyone he holds dear safe.