Shinichi Koga was a Japanese manga artist born on August 18, 1936, in Omuta, Fukuoka Prefecture. He began his career in the late 1950s, establishing himself as a prominent creator in the horror genre, particularly during the 1960s when he was considered a leading horror manga artist for girls alongside the renowned creator Umezu Kazuo, with the two often being called the genre’s "two pillars."

Koga is best known as the original creator of the seminal horror manga Eko Eko Azarak. The series was serialized in Akita Shoten’s Weekly Shonen Champion magazine from September 1975 to March 1979, spanning 19 tankobon volumes. The story follows Misa Kuroi, a high school student who is also a powerful witch, as she uses black magic to confront supernatural forces, demons, and her own dark past. The title itself references a Wiccan chant used by the protagonist in her spellcasting.

Following the original series, Koga continued to expand the story with sequel works, including Majo Kuroi Misa in 1982 and Eko Eko Azarak II, which began serialization in 1993. Beyond Eko Eko Azarak, his extensive body of work includes numerous other horror, mystery, and supernatural manga series such as Hakuja Yashiki (The White Snake Mansion), which ran in Weekly Margaret, Youchuu, Kyoufu no Kuchibashi, and Neko no Me Ningyou.

Eko Eko Azarak became the foundation for a significant multi-media franchise, inspiring numerous adaptations. Between 1995 and 2006, the series was adapted into six live-action films, beginning with Eko Eko Azarak: Wizard of Darkness in 1995. Koga himself became directly involved in these adaptations in later years, serving as a screenwriter for several entries, including the 1996 film Eko Eko Azarak II: Birth of the Wizard, the 2001 film Eko Eko Azarak: Awakening, and the two 2006 films Eko Eko Azarak: R-page and Eko Eko Azarak: B-page. The franchise also spawned two live-action television drama series, first in 1997 and then a 13-episode series titled Eko Eko Azarak -eye- in 2004. An anime adaptation, a two-episode original video animation (OVA) series, was produced by Toei Animation and released in 2007, for which Koga is credited as a writer. In 2011, he served as the director for a new live-action entry, The First Episode of Misa Kuroi.

Recurring elements across Koga’s work include the fusion of supernatural horror with psychological thrills, the use of witchcraft and occult themes, and a focus on strong protagonists who wield dark powers in a morally complex world. His series often blend a sense of dread with action and mystery. Koga’s significance in the manga industry lies in his foundational role in shaping the horror genre, particularly during its formative years in the late 20th century. His work, especially Eko Eko Azarak, has maintained a lasting cultural impact, with a remake manga series, Eko Eko Azarak Reborn, illustrated by Yamada Jta, running from 2020 to 2023, further cementing his legacy as a key figure in Japanese horror manga.

Shinichi Koga passed away on March 1, 2018, at the age of 81.