Here are several reputable papers and articles covering these themes: Academic & Scholarly Papers

: This capstone project from CSU Monterey Bay uses Queer Theory to analyze how diverse identities are depicted in both Japanese and American animation. In-Depth Critical Analysis

: An exploration on Sabukaru Online of how Japanese media allows for a wider range of character archetypes and "gender spicing" compared to Western media. Important Terminological Note

: A detailed piece from The Artifice that breaks down characters who identify as women despite being misgendered by others, such as Lily Hoshikawa from Zombieland Saga .

: Found on Medium, this article discusses how shows like Hourou Musuko (Wandering Son) provide sensitive, nuanced looks at transitioning and gender expression.

: This paper, available on ResearchGate, examines gender transitioning in anime and argues that some subgenres may reinforce binary gender concepts rather than being purely progressive.

In academic and respectful fan discourse, the term you mentioned is generally avoided. Instead, scholars typically use , Gender-nonconforming (GNC) , or Otokonoko (a specific Japanese term for boys who dress as girls). Using these terms in your research will help you find more credible, high-quality sources. Transfeminine Representation in Anime - The Artifice

: Published by the Illinois Open Publishing Network, this article analyzes works like Stop!! Hibari-Kun! and No Bra to understand the appeal of gender-ambiguous characters to both male and trans-feminine readers.