Sora is a mysterious blue-haired girl originating from Old Tokyo, a fragment of the city that catastrophically broke away thirteen years before the main events, now floating isolated in the sky above earthbound New Tokyo. Communication and travel between the two realms are impossible. As a resident of Old Tokyo, Sora uniquely perceives the imminent danger of the floating city hurtling back to the ground, threatening all its citizens. This foresight compels her on a perilous journey from Old Tokyo to New Tokyo to warn its inhabitants and prevent the disaster.

She encounters Kanata, a young man living with his grandmother after losing his parents in his youth. When unidentified beings attack Kanata, Sora saves him. She informs Kanata he is uniquely capable of saving the world and recruits him for her mission. Together, they form a team including the vampire siblings Touya and Yuna, and monsters Ryōma, Kamui, and Hanzō. This group unites to fight for the fate of both Tokyos.

During their journey, Sora demonstrates combat capabilities, wielding a scythe for area attacks and employing abilities like Chain Lightning, which delivers non-elemental shocks to multiple enemies. She also exhibits resistances to environmental hazards like fire. Her role evolves from a solitary figure driven by urgency to a collaborative leader coordinating the group's efforts against threats. The stakes of her mission intensify as the danger to Old Tokyo escalates, requiring strategic battles and alliances to avert the foreseen catastrophe.