Hongou is a student sent 6,000 years into the future as part of a team aiming to prevent human extinction by breaking an apocalyptic time loop. She travels with three other high school girls from a depopulated world, carrying only basic possessions that include non-functional toy-like cellphones. Journeying through a barren future landscape, Hongou and her companions encounter environmental anomalies like discolored rivers and unfamiliar birds while exploring remnants of abandoned settlements, including houses with identifiable markings. Their objective is to find a way to disrupt the cyclical apocalypse. Hongou operates within a larger initiative dispatching individuals to different time periods based on technological aptitude assessments; in the desolate future, her actions focus on collective exploration and survival with her teammates.