Tokiko Hishigata

Tokiko Hishigata (菱形 朱鷺子, Hishigata Tokiko) is Sou's younger sister, a first-year high school student. She is intelligent and has the top grades in her grade, but she is physically weak and not good at sports. She and Mio have known each other since childhood and are classmates at the same high school.

Appearance
Tokiko is a young girl with a long red hair braided in a tail.

Etymology

 * The name Tokiko means "crested ibis" (朱鷺) (toki) and "child" (子) (ko).
 * Part of the name Toki can also mean "vermilion red" (朱) (to) and "heron" (鷺) (ki) separately.
 * Tokiko's surname Hishigata means "Rhombus, diamond shape" (菱形).