Naze Boku no Sekai wo Daremo Oboeteinai no ka?

"Why does no one remembers the true world...!"

The era when the great race of the five tribes competing for hegemony on the ground ended with the victory of mankind led by hero Sid. However, that world was suddenly "overwritten" in front of a boy Kai. In the rewritten world, Kai saw the scene where humans lost to the five tribal war...