Five years ago, the earth was showered with peculiar bubbles defying gravity, each imbued with enigmatic powers. Following a massive unexplained blast, Tokyo found itself at the epicenter, encapsulated within a colossal bubble. The once-thriving capital of Japan now lay submerged in a gravity-altering ocean, deemed off-limits by the authorities, forsaken by its inhabitants. Orphaned children left in the aftermath of the 'Bubble Fall' now dwell illicitly in Tokyo, engaging in perilous parkour skirmishes amidst the city's decaying edifices. Among them is Hibiki, a standout in these adrenaline-fueled contests, possessing the rare skill to traverse between bubbles, who claims to catch whispers from the Tokyo Tower. Driven by a thirst for answers, he ventures towards the enigmatic sounds, only to plummet into the depths below. It is there that he encounters a mysterious girl, later christened Uta, who becomes his savior. Little does Hibiki realize that Uta's arrival in his life will unveil the truths shrouding the cataclysmic incident that reshaped their world irrevocably.