During World War II, he met author Yasuda Yojuro [ja], who encouraged him to pursue his interest in history and historical fiction with a career as a writer.

After the end of the war, Gomi completed his education at Meiji University, and began writing popular fiction with swordsmen of the Edo period as his protagonists.

He also created a character named Aoi Shingo, a fictional illegitimate son of shōgun Tokugawa Yoshimune, who travels around Japan in disguise, righting wrongs done by the government.

On January 31, 1964, he was involved in a head-on collision with a truck while driving on Japan National Route 1 at Suzuka, Mie, which left him hospitalized with internal injuries.

He was given a light sentence (18 months in prison, five years probation) partly due to a petition signed by numerous authors including Kawabata Yasunari, Shiga Naoya and Mishima Yukio.