Karen bears a resemblance to Hayato with most being able to tell that they're related to one another, she has black hair and purple eyes. At first, she is seen to be dressed in typical white hospital clothing as a patient.

As casual clothing, Karen is mostly seen to be dressed in a black and purple dress, light gray stockings and black multi-strapped boots. Having been treated for her illness, she is seen to be dressed in the middle school female uniform of Little Garden.

As a Slayer, she is dressed in a black variable suit. As an idol, Karen is dressed in a cute black and pink-colored frilled skirt with a white suit similar to that of a swimsuit without gaps.