In the year 2022, gamers rejoice as Sword Art Online - a VRMMORPG (virtual reality massively multiplayer online role-playing game) like no other - debuts, allowing players to take full advantage of the ultimate in gaming technology: NerveGear, a system that allows users to completely immerse themselves in a wholly realistic gaming experience. But when the game goes live, the elation of the players quickly turns to horror as they discover that, for all its amazing features, SAO is missing one of the most basic functions of any MMORPG - a logout button.

Lonely thirty-seven-year-old Satoru Mikami is stuck in a dead-end job, unhappy with his mundane life, but after dying at the hands of a robber, he awakens to a fresh start in a fantasy realm...as a slime monster! As he acclimates to his goopy new existence, his exploits with the other monsters set off a chain of events that will change his new world forever!

In Orario, fearless adventurers band together in search of fame and fortune within the monstrous underground labyrinth known as Dungeon. But while riches and renown are incentive enough for most, Bell Cranel, would-be hero extraordinaire, has bigger plans. He wants to pick up girls. Is it wrong to face the perils of Dungeon alone, in a single-member guild blessed by a failed goddess? Maybe. Is it wrong to dream of playing hero to hapless maidens in Dungeon? Maybe not.

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?