"Princess Knight" marks the first time Tezuka used his "story comic" format—which uses a narrative structure and cinematic techniques—in a "shōjo" manga. The series changed the concept of "shōjo" from gag comics or strips teaching "good behavior" to narrative-focused works, and thus is considered the first modern work of the genre. It also established elements that would be common in late works of the genre, including an idealized foreign (from a Japanese perspective) settings, a heroine with large eyes, and gender ambiguity with a certain amount of androgyny. In the 1970s, two trends were predominant in "shōjo" manga: the first featured "androgynous, masculine, or asexual protagonists searching for self and love", and the other had "more explicit romance involving an ordinary girl". Elements of both were already present in Tezuka's Sapphire.