Is It Wrong to Try to Pick Up Girls in a Dungeon?

Bell Cranel's rapid growth, his victory in the war games, and the increase in his family members, among other things, has lead to a continuing rise in the visibility of the Hestia Familia in the labyrinth town, Orario. With advances in the dungeon going well, they have arrived on the Nineteenth Floor - the labyrinth of the Great Tree. In the height of battle, Bell is forced to act solo and rescue a girl being attacked by monsters... But this trembling, crying girl is, herself, a monster.

Weine is a young vouivre, a dragon girl, who can speak and was attacked by monsters in the dungeon. Bell and the others took her with them to the surface and sheltered her in their Home. What is happening in the dungeon? Are there others like Weine? As some answers cannot be found above ground, Bell and the others enlist Aisha and Ryu's help and head back down to the 19th floor where he first met Weine in the Colossal Tree Labyrinth.

After her form was exposed in town, causing an uproar, Bell and the others managed to rescue Weine. As they confront the difficulty of sheltering her aboveground, the Guild charges the Hestia Familia with a compulsory mission - to go to the dungeon's Twentieth Floor and take Weine with them. Unable to figure out what the Guild is trying to do, and with no choice but to comply, Bell and the others head back down into the dungeon...

Monsters who can speak, who defy all that is known. Bell and the others receive a warm welcome from the Xenos. They are so strikingly different from human peoples in form, but they eat, drink, and have fun just as humans do. Seeing this strange sight, Bell and the others can't conceal their confusion. In the midst of the feast, Bell and the others are told by the leader of the Xenos, the lizardman, Lyd, of the Xenos' connection to the Guild, the particulars behind their current situation, and...their intentions...

Wiene has been separated from Bell and the others, left in the care of Lyd and the other Xenos. At the same time, the Xenos have divided into several groups in order to move to a different hidden village. The arachne Ranieh's group accompanies Wiene in the move, but they fall into an evil plot spearheaded by Dix, of the Ikelos Familia. One after another, they are slaughtered, and then the hands of evil reach for Wiene...

The Xenos are on a rampage to avenge Ranieh and the others, driving the town of Rivia on the Eighteenth Floor into destruction. At Ouranos' discretion, Bell has slipped into the suppression force, created with the Ganesha Familia at the core, and happens upon Lyd in the forest on the Eighteenth Floor. After hearing what happened, Bell offers to help in the search for Wiene, but Lyd rejects his offer and leaves. Ryu, who has caught up to Bell, recommends that he return to the surface. Bell makes his choice - to look for Lyd...and Wiene...

Bell and Fels chase after the Xenos and end up entering the man-made labyrinth, Knossos, the base of the Ikelos Familia. There, they watch as Dix's curse causes to the Xenos to unwittingly fight each other... and the madness of a man held prisoner by his cursed blood begins to reach toward Wiene... Meanwhile, on the Eighteenth Floor, the strongest Xenos begins to move, and not even high-level adventurers like Ryu and Aisha, or first-class adventurer Shakti, can stand in the way...

Tricked by Dix, Wiene heads toward the surface with Bell chasing after her. They are confronted by Ais and the Loki Familia who deem Wiene a threat to Orario... In the face of the city's strongest adventurers, the action Bell chooses to take is... to stand in their way and protect Wiene. To help Bell, Fels, Lyd, Gros, Rei, and the others all make their moves, but "the city's strongest" are an unscalable barrier blocking their way.

Thanks to Asterius joining the battle and Fels' revival magic, Wiene's death was averted and the Xenos narrowly escaped alive. However, Bell obstructed efforts by the subjugation force against the monsters who had emerged on the surface - a fact which will not be erased. Bell faces cruel words and harsh stares throughout all of Orario. Even worse, he receives information that the Xenos who came to the surface were unable to return to the dungeon and remain in hiding...

Bell and the rest of the Hestia Familia have decided to save the Xenos, helping them escape to Knossos and, through that, the dungeon. Making contact with Fels, who is traveling with the Xenos, helps them steadily advance their preparations. Meanwhile, the Loki Familia, and every other adventurer, is moving to stop them. Adding to all this are Eina, Aisha, Ryu, Hermes...and Ais. On this day, everyone carries their own convictions in their hearts, and the spark that will ignite the battle revolving around the Xenos is struck.

With the plan to evade the Loki Familia's tight defenses still in motion, Gareth's enters the battle resulting in Wiene being separated from Fels' group and chased by Tiona... Welf wields his magic swords and his life to stand against Gareth, but the difference in their abilities is clear. Meanwhile, Bell manages to shake Ais off his tail. He meets up with Haruhime, who has rushed out in fear of Wiene's safety, and the two of them search for Wiene together.

The Xenos have fallen into Hermes' trap, and Hermes has asked them to die. After hearing his divine intentions, a group of Xenos centered around Gros go out and act as he intends - running rampant on the surface. Seeing monsters running riot aboveground sends Orario into chaos. Eina works to give directions in the emergency evacuation while a Xenos' claws descend to rend her apart. And on Daedalus Street, a lone monster walks, steadily advancing... to meet the man who haunts his dreams.