Kōsuke Masuda is a Japanese manga artist and original creator, born on June 2, 1976. Although his birthplace is Aichi Prefecture, he was raised in Mie Prefecture. His career began with a focus on gag manga, a genre he pursued partly because it required drawing fewer pages than narrative-driven stories, which suited his developing artistic skills at the time. He first gained recognition by entering works in the Akatsuka Award, a contest for comedic manga. After receiving an honorable mention in the 49th Akatsuka Award, he made his professional debut in 1999 under the name Kōsuke Masuda.

Masuda is best known as the creator of the long-running series Masuda Kōsuke Gekijō: Gag Manga Biyori. The manga began serialization in Shueisha’s Monthly Shōnen Jump in January 2000 and continued there until the magazine ceased publication in 2007. It was then transferred to the newly launched Jump Square, where it ran until November 2014. The series continued under a new title, Masuda Kōsuke Gekijō: Gag Manga Biyori GB, starting in December 2014 and remains serialized in Jump Square. Shueisha has compiled the chapters into multiple collected volumes, with fifteen released for the original series and additional volumes for the GB continuation.

Beyond his signature work, Masuda has created other manga series. From 2011 to 2022, he wrote and illustrated Greek Mythology Theater: Days of the Gods and People, which was serialized in several magazines including Jump Kai and the literary magazine Shōsetsu Subaru. He also produced a semi-autobiographical essay manga, Anokoro no Masuda Kōsuke Gekijō: Gag Manga-ka Mezashi Biyori, which ran from 2019 to 2021.

The anime adaptations of Gag Manga Biyori form a significant part of Masuda’s creative legacy. The series has been adapted into multiple short-form anime television series. The first two seasons were produced by Artland, while later seasons, including the third, the fourth titled Gag Manga Biyori+, and the fifth titled Gag Manga Biyori GO, were produced by Studio Deen. The most recent season, Gag Manga Biyori GO, aired from April to June 2025, with Masuda credited as the original creator and also as the lyricist for its opening theme song. The anime adaptations are directed by Akitaro Daichi and are known for their fast-paced, five-minute episode format that mirrors the concise structure of the original manga.

Masuda’s artistic identity is defined by a hyperactive, nonsensical style of comedy characterized by bizarre plots, non-sequitur humor, and a narrative structure that jumps quickly to the punchline without lengthy setup. A recurring feature of his work is the modernized parody of famous historical figures, such as depictions of Prince Shōtoku as a beleaguered official or the poet Matsuo Bashō as a bumbling traveler. He has stated that he does not create stories around established characters; instead, he first conceives the plot and setting, then develops characters to serve the story. His personal interests, which include a fondness for animals such as cats, as well as his taste in music ranging from death metal to artists like Red Hot Chili Peppers and Guns N' Roses, are sometimes reflected in his work.

In the manga industry, Masuda holds a distinct position as a gag manga specialist who achieved sustained success with an unconventional, episodic format. His work has been acknowledged by fellow manga artists; for instance, the creator of Pyū to Fuku! Jaguar, Kyosuke Usuta, has cited Masuda as a unique talent whose work he had followed since his early award submissions. The Gag Manga Biyori franchise has maintained a consistent presence over two decades, with its most recent anime season airing in 2025, demonstrating the enduring appeal of his comedic style.