Ichijinsha is a Japanese publishing company that specializes in manga-related publications such as magazines and books. It was founded in August 1992 as Studio DNA with the purpose of editing shōnen manga. In January 1998, Studio DNA became a public company and shifted its focus from editing to publishing. Issaisha was formed in December 2001 as a publishing company that started Monthly Comic Zero Sum, a shōjo manga magazine. In March 2005, Studio DNA and Issaisha merged to form Ichijinsha. In October 2016, Ichijinsha was acquired by Kodansha and became its wholly owned subsidiary.