Ban Hikari has a genetic disease and has been given a year to live. Determined to make the most of the time she has left, she decides to bid farewell to everyone while secretly jotting down her aspirations in a notebook. Hikari's goal is to transform the remaining time into a remarkable journey, striving to turn each day into her best day ever. Consequently, those around her affectionately refer to her as the "Positive Monster." Hikari's penchant for undertaking audacious endeavors and embracing eccentricities not only attracts people to her but also inexplicably captivates everyone. Amidst her endeavors, Hikari finds herself entangled in an inexplicable bond with Fujiwara Taishi, a student from Class 3D, whom she deeply admires and loves.