The story takes place in a bustling city called Orario. There is an extremely large and complex maze under the city, which people call the dungeon. One day, the boy Bell met a girl named Hestia. The boy who had always wanted to be an adventurer and the girl who had always been looking for a family, the two hit it off and embarked on a wonderful adventure together. Bell has always believed that in the dungeon, he will meet his destined heroine, so on this day, at the moment of life and death, an adventurer named Ace appeared in front of him. This dramatic moment made Bell fall in love immediately. In addition to Bell and others, also active on the adventure front are the girl Lilyluka with a super high IQ, the blacksmith Welf, and the swordsman Yamato.