Ooki Kashihara dies trying to save a child and wakes up in a black-walled Tokyo apartment beside a handful of strangers who all died moments earlier. Akari Jinguu, who has been through this before, tries to explain the rules to the newcomers so more of them live through the night, and Ooki is the only one who listens and puts on the suit. Set before the main Gantz manga, this prequel novel follows their hunt for the Shotoku aliens and marks the first appearance of Nishi and Izumi.