Imagine being madly in love with the quiet cute girl in your class, slowly working up the courage to ask her out. She always spoke quietly in class and seemed shy, but you could tell she was as gorgeous on the inside as she was out.
Finally, you work up the nerve to say something and she smiles kindly and kisses your cheek, saying she would have loved it, then runs away. She stops coming to school. You finally find out where she lives and stop by but there's nothing there anymore.
You spend the rest of your days never finding out what happened to that lovely girl you knew while everyone else slowly forgot a quiet person named Sanae.