Koichi Endo is a Japanese manga artist known for creating gag comedies, primarily serialized in Shueisha's Weekly Shonen Jump during the 1980s and 1990s. He was born on September 28, 1956, in Niigata Prefecture. Endo made his professional debut in 1981 with a one-shot story called Day of Excursion (also known as Endoku no Hi), which was published in Shonen Champion. He soon began working with Shueisha, and his first major serialized work for the company was Ano Ano Tongarashi in 1983.

Endo is best known as the original creator of the manga and anime series Tsuide ni Tonchinkan (also spelled Tsuideni Tonchinkan), which translates to Anyway, It Does Not Matter. This gag manga was serialized in Weekly Shonen Jump from 1985 to 1989, with its chapters later collected into eighteen tankobon volumes. The series follows the exploits of a group of junior high students and their teacher who collectively assume the identity of the phantom thief Tonchinkan, though the focus gradually shifted towards slice-of-life school comedy as the series progressed. Endo was aware of this thematic shift and even included a self-referential gag about the change in the manga itself.

The success of the manga led to a forty-three episode anime television adaptation. Produced by NAS and Fuji Television and animated by Studio Comet, the series aired on Fuji TV from October 10, 1987, to October 1, 1988. In the production of the anime, Endo is officially credited as the original creator, with Yuzo Yamada serving as chief director and Takao Koyama handling series composition.

Following the conclusion of Tsuide ni Tonchinkan, Endo continued creating manga for Shueisha. He wrote and illustrated a sequel titled Miracle Tonchinkan, which was serialized in Monthly Shonen Jump from 1991 to 1996 and compiled into four volumes. He also created the series Original Quest, which ran in the same magazine from 1994 to 1995 and was collected into a single volume. Throughout his career, Endo maintained a focus on gag comedy, often incorporating absurdist humor and parody elements into his work. According to production notes for Tsuide ni Tonchinkan, Endo expressed a deliberate intention to draw a gag manga, and the phantom thief concept emerged after one of his initial comedy ideas was rejected by his editor. His other known works include Little Shinigami, Little -God in training-, and End Zone.

Koichi Endo's significance in the manga industry lies primarily in his contributions to Weekly Shonen Jump during a vibrant period for the magazine in the late 1980s. Tsuide ni Tonchinkan represents a successful example of a long-running gag series from that era, demonstrating the viability of pure comedy within a magazine best known for action and adventure titles. The series received a full anime adaptation and spawned a sequel, marking Endo as a creator who successfully transitioned from page to screen with a sustained comedic vision.