She has hair with a distinct streak in her bangs and a blunt personality, but she is kind-hearted and deeply compassionate at her core. While she is female, her combat form involves transforming into "Senketsu," a suit of living steel; however, the increased exposure in that form makes her look like a total exhibitionist. Even for a tomboy like her, the outfit is embarrassing enough to make her turn bright red. Normally, she wears "Senketsu" as a short-cropped sailor uniform with her skirt held up by suspenders. Interestingly, she seems to be afraid of needles.

The student council president who rules Honnouji Academy through force and fear. Her mother is Ragyo Kiryuin, the academy's chairwoman and CEO of REVOCS, a corporation that controls 70% of the world's apparel industry—making Satsuki a true high-class lady. She is a woman with a sharp, powerful face characterized by long black hair and dignified, thick eyebrows. Her personality is that of a true ruler: severe, fierce, and majestic. She always carries her beloved sword, "Bakuzan," and maintains total control over the students and their families through various means of power. In battle, she transforms to fight just like Ryuko Matoi. With a beautiful physique that rivals Ryuko's and a white-and-blue color scheme, her design serves as a direct counterpart to Ryuko's. However, her outfit is equally revealing.