After a victorious war between five distinct earth races, humans emerged triumphant, sealing the defeated races in the Crypts under Prophet Sid's guidance. Kai's duty entails safeguarding these crypts and preparing to defend humanity when the sealed races resurface. Amidst the tranquil crypts, a sudden shift transforms Kai's reality with the activation of 'World Rebirth.' Now stranded in an unfamiliar realm where his existence is a mystery, Kai grapples with the burden of remembrance in a world oblivious to his identity.