On the day Haruki entered university, he had a fateful encounter with Sakura in the classroom. The two fell in love and decided to live together after graduation. However, their separation came suddenly. Sakura vanished from this world... Five years later, in the season of the fifth cherry blossom bloom, Haruki, still lost in despair, accidentally discovers a diary. It is the diary of the ten years that Sakura could not conclude.