The year is 2027, and Kyoto has seen significant technological improvement. Naomi Katagaki, a socially awkward and shy lad with a love of books, and Ruri Ichigyou, a girl with a chilly demeanor who is sometimes abrupt with others but shares his love of reading, reside in the city. Despite their shared hobbies, Naomi is hesitant to approach Ruri owing to her unpleasant demeanor. When Naomi goes for a stroll one day, a red aurora pierces the sky for a brief instant before disappearing. Soon after, he encounters a three-legged crow and a mystery hooded guy who shows himself to be Naomi from ten years in the future, claiming that he has come to prevent a sad occurrence that is about to occur.