Futanari? What's that?

What do you know about Futanari?This is a book for those who have "heard of it but don't know much about it" and those who "love it so much I want to know more about it".Etymology, thesaurus, misuse, language, worldview, examples of works, expressions, etc... I discuss and explain topics related to futanari from various perspectives. It is not only aimed at a general audience, but also has parts relevant to the creators, including ideas for drawing futanari in a more attractive way!Note: Includes clean illustrations from the book as an extra download!