There's a catfish under Japan, and when it rolls the land rises and falls. At least that's what Sora was told after she lost her mother to an earthquake so powerful that it cracked time itself. Sora and her father are some of the few who still live near one of these "zones"--the places where time has been irrevocably sped up or slowed down.

Sora's father leads a research team studying the zones, and even as his colleagues begin to fall ill, he refuses to stop entering the zones himself. Sora finds herself stuck and increasingly alone as her father starts behaving strangely--he's disoriented and his memory seems to be deteriorating. Sora, meanwhile, has been secretly conducting her own research on the zones, tracking down a time expert in Tokyo and surprising herself with a crush on a strikingly confident girl named Maya, another hafu girl with whom she forms an instant bond.

But when Sora's father disappears, she has no choice but to return home, with Maya in tow, and venture deep into the abandoned time zones to find him and perhaps the catfish itself . . .