It is evening on the train. This line runs through the countryside and has few passengers; by the time it nears the final stop, there are usually only a few people left on board. Among them is a high school girl who always takes the same train at the same time. Having naturally spent a lot of time in the same carriage, you know each other's faces, but you have never spoken. Feeling a slight awkwardness, you sit in your usual spot—but today, for some reason, she enters this specific carriage out of the three available. And of all the empty seats, she chooses to sit right next to you.