Keita Amemiya is a Japanese character designer, director, and screenwriter born on August 24, 1959, in Urayasu, Chiba, Japan. He graduated from the Art College Asagaya and began his career in the film industry in 1981 when he joined Den Film Effect. Amemiya is widely recognized for creating the dark fantasy tokusatsu series Garo, but his work as an original creator extends into several notable anime and manga projects.

As an original creator in animation, Amemiya is best known for developing the television series Tweeny Witches, also known as Mahō Shōjo Tai Arusu. Produced by Studio 4°C, the series aired 40 episodes from April 2004 to March 2005 and follows a young girl who finds herself trapped in a magical world. He is credited as the original creator for this series, which later spawned an original video animation titled Tweeny Witches: The Adventures, released in 2007 across six episodes. His role as a creator establishes the foundational concepts and settings that other directors and writers then adapt into finished productions.

The Garo franchise stands as his most significant and expansive creation. Beginning with the 2005 live-action tokusatsu series, Amemiya originated the property, which has since generated numerous sequels, spin-offs, and anime adaptations. Among these are the animated film Garo: Divine Flame, released in 2016, where he is listed as the original creator. Another anime film in the franchise, Usuzumizakura -Garo-, released in 2018, also credits Amemiya with the original story. These productions demonstrate how his original concepts have been translated across different media and production studios. An earlier original video animation titled G-9, from 2006, similarly credits Amemiya as both the original creator and director, further illustrating his hands-on involvement in translating his own concepts into animated works.

Beyond his role as a creator of original properties, Amemiya has also worked on established franchises as a character and monster designer. He contributed character designs for Kamen Rider BLACK and its sequel Kamen Rider BLACK RX, as well as directing the live-action films Kamen Rider ZO and Kamen Rider J. His video game work includes character designs for titles such as Clock Tower 3, the Onimusha series, and Shin Megami Tensei IV, demonstrating a consistent visual signature across interactive media as well.

Amemiya is known for a distinctive visual style that blends fantasy elements with intricate mechanical and creature designs, often described as dark or gothic in tone. His background in tokusatsu and live-action effects informs the aesthetic of his animated projects, creating a unique cross-pollination between practical suit design and drawn animation. He has also made appearances at international conventions, including Anime Expo in 1993 and a scheduled appearance at Anime NJ++ in November 2025, indicating his lasting influence and recognition among genre fans.

Throughout his career, Amemiya has functioned primarily as a visual creator and director rather than a writer of prose or manga, with his strength lying in the conception of worlds, characters, and their visual presentation. The adaptation history of his works shows a pattern where his original ideas are often realized by different directors and studios while he retains creator credit, as seen with Tweeny Witches being directed by Yoshiharu Ashino and various Garo anime entries being helmed by different directors. This division of labor highlights his role as an originator whose concepts are robust enough to be interpreted by other artists while maintaining a coherent creative identity.