"I must not be late! I made a promise to my childhood friend Natsuhe Shinomiya, who is a year older than me, that if I was late, I would be severely punished... For making my beloved wait." After a while, however, our relationship had to be temporarily interrupted because we were in different schools. A year passed and I was looking forward to seeing my beloved... But time inexorably changes people, and that girl was no longer my Natsu-chan...