Sawatari Kasumi

Twin sister. Contrary to her older sister Nadeko, she is a vivacious and sociable woman.

Because of her caring and cheerful personality, she is well-liked by people of the same sex and has many friends. She is kind and tender toward her younger brother, just like her sister Nadeko.

However, her expression of affection is like that of an elementary school student who bullies her favorite child, and she enjoys bullying the protagonist every chance she gets, taking advantage of the fact that she is his older sister and that he is older than her.