Themes associated with "yuri" originate from Japanese lesbian fiction of the early twentieth century, notably the writings of Nobuko Yoshiya and literature in the Class S genre. Manga depicting female homoeroticism began to appear in the 1970s in the works of artists associated with the Year 24 Group, notably Ryoko Yamagishi and Riyoko Ikeda. The genre gained wider popularity beginning in the 1990s; the founding of "Yuri Shimai" in 2003 as the first manga magazine devoted exclusively to "yuri", followed by its successor "Comic Yuri Hime" in 2005, led to the establishment of "yuri" as a discrete publishing genre and the creation of a "yuri" fan culture.