Tate no Yuusha no Nariagari (WN)

Tate no Yuusha no Nariagari (WN) summary:

Naofumi Iwatani, an uncharismatic Otaku who spends his days on games and manga, suddenly finds himself summoned to a parallel universe! He discovers he is one of four heroes equipped with legendary weapons and tasked with saving the world from its prophesied destruction.
As the s.h.i.+eld Hero, the weakest of the heroes, all is not as it seems. Naofumi is soon alone, penniless, and betrayed. With no one to turn to, and nowhere to run, he is left with only his s.h.i.+eld. Now, Naofumi must rise to become the legendary s.h.i.+eld Hero and save the world!