“Have you ever heard of memento mori?”“It means that you should always remember that you too will die someday.”When I was in high school, I was in love with a mysterious girl.She seemed cold but also thoughtful at the same time, and she seemed to be smart yet somehow a bit goofy at times. She had many secrets and she never told me what those secrets were. When I told her, , she welcomed me and we made many happy memories.Until a car accident took her away from me.And 10 years later, I found myself being a teacher.Maybe it was a cruel twist of fate, but on the first day that I have been assigned to my alma mater, I was heading towards the old school club room where I used to hang out after the day was over.[……Not a thing has changed]As I turned away with some tears running down my cheeks out of sentimentality,“Are you heading back already?”……Suddenly,I heard a voice that I have missed for so long.When I looked back, I saw her looking the same as she was 10 years ago,but now, she was a ghost.