Hiroyuki Etō is a Japanese manga artist and original creator, best known as the author of the Mahōjin Guru Guru (Magical Circle Guru Guru) series. His work as the original creator is directly tied to the anime adaptations mentioned, including the 1994 Mahōjin Guru Guru, the 2000 Doki Doki Densetsu Mahōjin Guru Guru, and the 2017 Mahōjin Guru Guru series.

Etō was born in Taketa City, Ōita Prefecture, Japan, and later grew up in Ōita City. After high school, he attended Musashino Art University but eventually withdrew. His debut as a manga artist came in 1985 with a short piece published under the name Ninotika Hiroyuki. Before establishing himself as a manga creator, he worked as a game writer and illustrator. In 1990, he began contributing to the Dragon Quest 4-Koma Manga Theater, a popular anthology of comedic strips based on the Dragon Quest video game series, which helped him gain recognition for his unique drawing style and sense of humor.

Etō began serializing his signature work, Mahōjin Guru Guru, in Enix's Monthly Shōnen Gangan magazine in July 1992. The series ran until August 2003 and was compiled into sixteen tankōbon volumes. The manga is a fantasy comedy that parodies the conventions of role-playing games, particularly the Dragon Quest series, using in-game-style message boxes for comedic effect. The story follows the young hero Nike and the apprentice mage Kukuri, who uses a unique form of magic called Guru Guru, as they embark on a quest to defeat the demon king.

The success of the manga led to multiple anime adaptations. The first anime series, produced by Nippon Animation, aired for forty-five episodes from October 1994 to September 1995. This was followed by a second series, Doki Doki Densetsu Mahōjin Guru Guru, which ran for thirty-eight episodes from April to December 2000. A third anime adaptation, produced by Production I.G, aired for twenty-four episodes from July to December 2017. In addition to the manga and anime, a theatrical anime film was released in April 1996.

After a period of reduced activity beginning in 2004, Etō returned to the Guru Guru universe. He serialized a spin-off titled Buyōden Kita Kita on the Gangan Online website from 2008 to 2012. Immediately following the spin-off, he launched a direct sequel, Mahōjin Guru Guru 2, on the same platform in November 2012. The sequel concluded in July 2025 after a long serialization run, spanning twenty-one volumes. As of 2024, the Guru Guru series as a whole has sold over fifteen million copies.

Beyond Mahōjin Guru Guru, Etō has created other manga series, including Gadget, which was serialized in Monthly Comic Blade from 2002 to 2005. He is notable for being the only manga artist who, during a period of corporate restructuring between Enix and Mag Garden, held concurrent serializations in both Monthly Shōnen Gangan and Monthly Comic Blade.

Etō’s artistic identity is closely tied to a whimsical and parodic style that blends fantasy with video game logic. His work often features exaggerated comedic expressions and recurring gags. His personal interests in DJing and electronic music have also influenced his career; he performs as a DJ under the name NICK-Q and has composed music for works related to his franchise, including the theme song for the 1996 Mahōjin Guru Guru film. A notable figure in the industry, the acclaimed manga artist Hiromu Arakawa, creator of Fullmetal Alchemist, worked as an assistant for Etō from 1999 to 2000.