Sumiko is statuesque tall, voluptuous and gorgeous woman with a curvy and slender hourglass figure with a narrow waist and large, broad hips. She has fair skin and long, luxurious white hair and bright blue eye.

She was stern, earnest, and thoughtful, to the point where Satoru questioned if she was really his twin.

Very outwardly aloof, and calculating individual. She usually has a neutral facial expression that she rarely changes, making it appear as if she takes every situation seriously.