Kiyumi no shishuu Sayuru no shishuu

After school, Kiyumi and Sayuru ride their bicycles to their meeting place, take off their bicycle seats with a wrench, and go off to play with their seats held in both arms so that it will not get stolen. One day when the two girls forgot to remove their bicycle seats, they come back and only Sayuru’s seat was missing. Since then, Kiyumi has disappeared from Sayuru’s world.