Firehead is the original creator behind several light novel, manga, and anime series, recognized primarily as the author of the stories that form the basis for these works. Active since the mid-2010s, Firehead began by serializing narratives on the user-generated novel publishing website Shōsetsuka ni Narō, a common starting point for many successful light novel authors.

The most prominent work associated with Firehead is A Wild Last Boss Appeared! (Yasei no Last Boss ga Arawareta!). The original story was serialized as a web novel on Shōsetsuka ni Narō from October 2015 to April 2019. It was subsequently acquired for print publication as a light novel by Earth Star Entertainment, with the first volume released in February 2016 and the ninth and final volume in April 2019, featuring illustrations by YahaKo. The series has also been adapted into a manga illustrated by Tsubasa Hazuki, which began serialization in 2017. An anime television series adaptation was announced in August 2024, with a scheduled premiere in October 2025.

Firehead is also credited as the writer for Mercedes and the Waning Moon (Kaketa Tsuki no Mercedes). This series also originated as a web novel on Shōsetsuka ni Narō, running from October 2018 to November 2022. The light novel adaptation, illustrated by KeG, has been published by TO Books since May 2021, with four volumes released as of August 2025. A manga adaptation illustrated by Pochi Edoya began serialization in August 2021, and an anime adaptation for this series was announced in August 2025.

Both of Firehead’s major works fall within the isekai genre, featuring protagonists who are reincarnated or transported into fantasy worlds. A recurring element in these series is the concept of a character navigating a new life within the framework of game-like mechanics and lore. For A Wild Last Boss Appeared!, the narrative involves a person waking up in the body of their former in-game character, the fearsome overlord Lufas Maphaahl, in a world that has become real. Similarly, Mercedes and the Waning Moon follows a protagonist reincarnated as a young vampire aristocrat who turns to dungeon crawling to secure her future. Both series have seen significant commercial success, with A Wild Last Boss Appeared! reportedly selling over one million copies of its light novel volumes.

Within the industry, Firehead’s significance is marked by the transition of two distinct original works from web novels to published light novels, manga adaptations, and ultimately to anime productions. This trajectory demonstrates a sustained level of popularity and commercial viability. In a statement regarding the anime adaptation of A Wild Last Boss Appeared!, Firehead expressed anticipation for seeing the characters and world realized in animation, thanking the supporters who made the project possible.