Sagara Sousuke isn't your typical high school student. He reads military enthusiast magazines; he responds to questions with "affirmative;" he brings grenades to school in his bag. Though everyone at school takes him for a hopeless military geek, Chidori Kaname thinks there might be something more to him. When their plane is hijacked in the middle of a field trip, Kaname's instincts will prove correct: Sousuke is an elite, mech-piloting mercenary... and he's here to protect her!

From his deathbed, Hero-King Inglis, the divine knight and master of all he surveys, gazes down on the empire he built with his mighty hand. Having devoted his life to statecraft and his subjects' well-being, his one unfulfilled wish is to live again, for himself this time: a warrior's life he'd devoted himself to before his rise to power. His patron goddess, Alistia, hears his plea and smiles upon him, flinging his soul into the far future.

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 Shield 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 shield. Now, Naofumi must rise to become the legendary Shield Hero and save the world!

Naofumi Iwatani continues his adventure in this second volume. But his task is not yet complete and obstacles mount as the increasingly ominous waves of destruction approach. He finds a new friend and new powerful abilities that may prove to be too dangerous for the companionship. Will Naofumi live up to his role as the Shield Hero and save the world from its prophesized destruction? Or will his dark side consume him?

One day, the life of middle-aged Japanese businessman Ryoma Takebayashi came to a rather sudden and disappointing end. Ryoma had never had a blessed life, but after his death, three great gods sought his cooperation and reincarnated him as a child in another world with swords and magic!