The story follows a 34-year-old man who is killed after trying to save someone from getting hit by a car. He soon finds himself reincarnated in a magical world as Rudeus Greyrat, except that he gets his whole life reset, starting as a baby.
With all of his knowledge from his previous life, and a new heaping helping of magical ability, Rudeus quickly becomes a formidable warrior ready for adventure. Oh, and he's still a total pervert.
In a world, where the deities have descended from the heavens lies the town of Orario that features the Dungeon, which contains an assortment of monsters from goblins to dragons. Adventurers slay those monsters and take their shards, which are then used to craft magic items. To become an adventurer, people join groups called Familia. Each of which is named after and serves a resident deity. The adventurers and their attributes and abilities are ranked by level, improved by experience and supervised by their Familia's deity.
Bell Cranel, a novice adventurer, is the sole member of the Familia under the goddess Hestia. After being saved by top level adventurer Ais Wallenstein of the Loki Familia, he falls in love with her and decides to improve and become worthy of her attention. All the while mostly unaware that other girls, deities and mortals, also develop feelings for him. Especially Hestia herself.