Maji Brother!?

Hasuno Miu, a high school teenage girl, loves her big brother, Keiichiro, and believes he is the gentlest and kindest person ever. Miu learns that there is a suspicious pervert lurking around the community and, to her surprise, stumbles upon a couple that matches that description. Miu escapes back to her house only to find that the man and the woman is none other than her brother Keiichiro and his summoned demon sex slave Manimani. It turns out that Keiichiro is a magician that was able to summon Manimani from the depths of hell. With everything she thought of her brother shattered into oblivion, Miu has no idea what to do.