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.

Plot
Tokiko joins Sou, Mio and Shinpei to visit the Summer Festival with them. Per Sou's request, she helps Mio to dress in yukata and they go pick up Shinpei. At the festival, Mio wonders what Sou and Shinpei are talking and panicking, Sou states they are discussing what they like more, butts or boobs, which makes Mio give Shinpei a strange look. Shinpei tries to deny it, but Tokiko states that's interesting conversation and reveals that Shinpei came in the bathroom while Mio was taking a bath, but Shinpei states he didn't see anything. Tokiko then wonders what Shinpei feels about Mio and he reveals he cares for her as a family. Mio then stops Tokiko from asking any other questions. Shinpei then sees something and runs and leaves the group. After the fireworks, Mio calls Shinpei and he rejoins them. They watch the ceremony and after it, Sou wants to confess to Mio. Tokiko tells Shinpei about it, but states it won't go well as Mio already loves someone else, but refuses to tell Shinpei who that is. After Sou confesses and Mio states he just wants to be friends, Ushio appears. Mio thinks she is a shadow and warns Shinpei, but Shinpei reveals that he himself is a shadow.

Other shadows appear and they start killing people. The real Shinpei appears and sees the blood. Tokiko starts crying and apologizes, saying that this wasn't why she dirtied her hands, but then she gets killed by a shadow.

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).