It is believed that Nobuko Yoshiya was one of the first anime creators to introduce the concept of yuri relationships. In most of Yoshiya's stories, the girl/girl relationships were emotionally strong but still platonic, nonetheless, suggesting that such a relationship was simply part of a woman's development toward eventual heterosexual love.
Yuri relationships began appearing more frequently in anime and manga stories during the 1970s, usually featuring an older woman's attraction to a younger one. Almost all such relationships depicted in this time period ended in tragedy, likely reflecting how the Japanese culture was struggling to accept homosexuality.
By the 1990s, the depiction of yuri began to change, as such couples started being depicted as more positive and publicly open in-story. The yuri relationships in the popular anime series "Sailor Moon" and "Revolutionary Girl Utena" are two widely known examples.
Many audiences and observers of anime in North America have taken the term "yuri" to mean only a full sexual relationship between two female characters. Some even go so far as to believe true yuri is only depicted in the most explicit forms, but this would only be shown in adult-themed "hentai" shows.
Many anime shows have had any descriptions of yuri toned down in order to be shipped overseas to America. This is largely because of the constant controversy and debate in the United States regarding homosexuality, combined with the widespread public belief that animated shows are still primarily for young audiences. A prime example was "Sailor Moon," where two female characters who were a lesbian couple had to be changed to "cousins" in the English dub.