Bunny girls do not live in libraries. This is simply common sense. And yet, that's exactly where Sakuta finds one in the wild. More bewildering is who the bunny girl is: Mai Sakurajima, a girl one year older than Sakuta, famous at their school for her acting career even though she's currently on break. To top it all off, it seems like no one else in the library can see Mai at all, no matter what she does or...wears.

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.

Kicked out by his family and wandering the streets, an unemployed 34-year-old shut-in thinks he’s hit rock-bottom—just as he’s hit and killed by a speeding truck! Awakening to find himself reborn as an infant in a world of swords and sorcery, but with the memories of his first life intact, Rudeus Greyrat is determined not to repeat his past mistakes. He’s going to make the most of this reincarnation as he sets off on the adventure of a second lifetime!

The life of a traveling merchant is a lonely one, a fact with which Kraft Lawrence is well acquainted. Wandering from town to town with just his horse, cart, and whatever wares have come his way, the peddler has pretty well settled into his routine - that is, until the night Lawrence finds a wolf goddess asleep in his cart. Taking the form of a fetching girl with wolf ears and a tail, Holo has wearied of tending to harvests in the countryside.

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.