There are numerous theories regarding the circumstances of their creation and themes, but the humorous animal caricatures of the first volume are particularly outstanding and considered to be the origin of modern Japanese Manga culture.
制作事情、主題等については諸説あるが、特に甲巻のユーモラスな動物戯画は秀逸で、現代日本の漫画文化のルーツとも見なされる。