In the rewritten world, Kai saw the scene where humans lost the five tribal wars because of the absence of hero Sid.
The novel series began in 2017 under MF Bunko J with three volumes published so far while the manga began serialization in Comic Alive in 2018 with two volumes published so far.
The era when the great race of the five tribes competing for hegemony on the ground ended with the victory of mankind led by the hero Sid.