A high school girl with a terminal illness opts to make the most of her few remaining months, be cheerful and experience as much as possible before it is all too late. She has a crush on a class-mate and acts on her impulse. She loves her best friend and receives loyalty in return. She brings wonder to those around her. Part of her disposition is owing to her superstitious beliefs and the diary she is leaving behind, which acts as a letter to her sullen school crush.