Koshigaya Natsumi Seventh grader at Asahigaoka Branch School. Uses a green/red memorization ruler (which blocks the red answers in the textbook). Never once has she used it as originally intended Miyauchi Renge First grader, the youngest of the five students at Asahigaoka Branch School. Uses an orthodox plastic ruler Also uses it for arithmetic.  Koshigaya Komari Natsumi's older sister, eighth grader at Asahigaoka Branch School. Uses a bamboo ruler. A gem that she inherited from her mother, it's been passed down through the generations of the Koshigaya family. Ichijo Hotaru Fifth grade transfer student from Tokyo. Uses an isosceles triangle ruler from a ruler set. It was selected with balance in mind.