The story is set in Aquafall, a fantasy world abound with water and greenery, and populated by dragons and fairies. Meteorites suddenly bring forth evil creatures that threaten all living things on the planet. The fairy Syrup assembles the Aquafall Defense Force, with three girls of the dragon clans as recruits. The story follows Syrup and the dragon girls Leviathan, Bahamut, and Jörmungandr as they work together to battle enemies and grow up. (Source: ANN)

Upon his run-in with a Vouivre—a monster known to be very dangerous—Hestia Familia's captain Bell Cranel is struck with incomprehension. Despite its preceding reputation, the supposed bloodthirsty creature happens to be crying and flees from a group of adventurers. The monster, taking the form of a terrified little girl, prompts Bell to swiftly decide to hide her. Unbeknownst to him, this act of kindness will cause massive repercussions that will soon echo throughout the entire city of Orario.

It is business as usual in the massive city of Orario, where legions of adventurers gather to explore the monster-infested Dungeon. Among them is the easily flustered yet brave Bell Cranel, the sole member of the Hestia Familia. With the help of his demi-human supporter Liliruca Arde and competent blacksmith Welf Crozzo, Bell has earned the title of Little Rookie by becoming Orario's fastest-growing adventurer thanks to his endeavors within the deeper levels of the Dungeon. Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka II continues Bell's adventures as he tries to bring glory to his goddess and protect those he cares about. However, various familias and gods across the city begin to take notice of his achievements and attempt to add him to their ranks.

Second part of Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka IV.