Fujino Ōmori is a Japanese novelist best known as the original creator of the popular fantasy light novel series Is It Wrong to Try to Pick Up Girls in a Dungeon?, also known as DanMachi. He launched his career by submitting the story, then titled Familia Myth, to the 4th GA Bunko Award, where it won the grand prize and secured a publication deal. The first light novel volume was published by SB Creative under their GA Bunko imprint on January 15, 2013. While his exact birth date is not public, he mentioned in an afterword from 2018 that he was under thirty years old at the time.

The DanMachi series serves as Ōmori's flagship work and has expanded into a large multimedia franchise. The original light novel series, illustrated by Suzuhito Yasuda, remained ongoing as of late 2025 with twenty-one volumes. The story follows the young adventurer Bell Cranel in the dungeon-centric city of Orario, and Ōmori has been praised for keeping the narrative engaging across many volumes by varying the settings and challenges, from dungeon expeditions to conflicts between divine familias. Beyond the main series, he also writes the spin-off light novels Is It Wrong to Try to Pick Up Girls in a Dungeon? On the Side: Sword Oratoria, which follows the powerful Loki Familia concurrently with the main plot, and the Familia Chronicle series, which focuses on individual side characters.

Ōmori's works have seen extensive adaptation into other media. The DanMachi anime television series, produced by studio J.C.Staff, began airing in April 2015. The series has continued through five seasons, with the fifth adapting the Goddess of Fertility Arc and concluding in March 2025. For the fourth and fifth seasons, Ōmori is credited as a writer alongside Hideki Shirane, indicating his direct involvement in the anime production. He also wrote the screenplay for the 2019 theatrical film, Is It Wrong to Try to Pick Up Girls in a Dungeon?: Arrow of the Orion. Multiple manga adaptations of the series have also been serialized, primarily in Square Enix's Young Gangan magazine.

In December 2020, Ōmori launched a second major property, the manga series Wistoria: Wand and Sword, with illustrations provided by Toshi Aoi and serialized in Kodansha's Bessatsu Shōnen Magazine. The story centers on Will Serfort, a swordsman navigating a magic-dominated academy. An anime adaptation of Wistoria aired its first season from July to September 2024, and a second season has been announced. A light novel adaptation of Wistoria was also published under the GA Bunko imprint in July 2024. Through these projects, Ōmori has established himself as a significant creator in the fantasy genre, known for blending traditional dungeon-crawling adventure with character-driven narratives and for his active role in shaping the adaptations of his work across multiple media platforms.