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!

A certain college girl who's loved books ever since she was a little girl dies in an accident and is reborn in another world she knows nothing about. She is now Myne, the sickly five-year-old daughter of a poor soldier. To make things worse, the world she's been reborn in has a very low literacy rate and books mostly don't exist. She'd have to pay an enormous amount of money to buy one.

A bicycle crashes into me one night, and the next thing I know, I’m a baby? Getting reincarnated in another world populated by humans, demi-humans, and mythical beasts is certainly not the turn I thought my life was going to take. I especially didn’t expect to be carried off by a wolf and given into the care of a one-armed former knight. Now, I’m trying to repay him by rebuilding the family inn and healing his arm with alchemy.

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!