Sugomori City- a fictional city in Japan- was constructed on reclaimed land but over time, its population dwindled. One day, Sonosaki informs her fellow classmate, Katsuhira, that he has been handpicked to become a Kiznaiver. The Kizuna System enables Katsuhira to share his injuries with his classmates, who have vastly different lifestyles and characters from his. The Kizuna System is an imperfect tool for achieving world peace that links people through injuries, with all users of the system being referred to as Kiznaivers. When a Kiznaiver is harmed, the system disperses the damage among the other Kiznaivers.