My brother couldn't be a corrupted magical girl.

My brother's phone is full of magical girl comics. Is he going through puberty?
As her younger sister, I can understand...
My brother has a rare, priceless magical girl dress hidden in his wardrobe—it's a rather unusual fetish of his.
As her younger sister, I can understand...
But when the older brother transforms into a villainous magical girl and appears on the battlefield...
As the younger sister, I really don't understand...
When did my stupid older brother become so corrupt?!