Kazumasa Kiuchi is a Japanese manga writer and scenario writer born in 1958 in Fukuoka Prefecture, Japan. He is a graduate of Fukuoka University. Kiuchi is known for creating original manga series that have been adapted into other media, most notably the original work for the anime OVA Emblem Take 2. He is the older brother of fellow creator Kiuchi Kazuhiro.

Kiuchi began his career as a manga author in 1990 with the series Emblem Take 2. The manga, illustrated by artist Jun Watanabe, was serialized in Kodansha's Weekly Young Magazine and ran for an extensive 62 volumes, concluding in 2004. The story follows a yakuza who travels back in time to correct past mistakes but finds himself unable to change his fundamental nature. The success of the manga led to a two-episode original video animation adaptation released between 1993 and 1995, for which Kiuchi is credited as the original creator. A live-action film adaptation was also produced.

Beyond Emblem Take 2, Kiuchi has been involved in several other manga and anime projects throughout the 1990s and 2000s. His manga works include Blue Dragon from 1995, Para from 1998, Out Law from 2004, and Chill from 2006. In 1998, he created Para, a three-volume series illustrated by Yutoku Inoue, which was serialized in Young Magazine Uppers. The manga uses a body-swap premise, where a young carpenter gains the ability to temporarily inhabit the bodies of nearby women, leading to storylines that blend action, comedy, and espionage.

Kiuchi has also worked on the Be-Bop High School franchise, a series of OVAs that ran from 1990 to 1998. He served as a producer on the main OVA series, wrote the scripts for the first three episodes, and handled planning for the Be-Bop High School Kaizokuban OVAs. His career reflects a consistent focus on seinen manga aimed at adult male readers, often featuring protagonists involved in criminal underworlds or absurdist action scenarios.