The Hero Is Overpowered but Overly Cautious light novel Volume 4

Robots versus Golems!

Rampaging past his limits in his new Berserk Mode, Seiya emerges victorious from the battle with the Beast Emperor, Grandleon! But his struggles in the revamped world of Ixphoria have only just begun...Next on the chopping block is the Machine Emperor, Oxerio. His high-tech arsenal, replete with tens of thousands of killing machines, threatens to wipe Termine Kingdom off the map! Fortunately, Seiya's got a secret weapon! ...Sort of.