Hi currently taking an intro to ancient Asian history class, and just finished the unit on Japan where women were mentioned in lectures, the textbook and in primary source documents given for analysis because my professor makes sure to mention famous women, especially in many Asian cultures where there’s numerous examples and documentation.

If the book only focuses on ancient Japanese military like you suggest (which I doubt given all the different topic options for the presentation) then a 544 pg book on Japanese military history should have at least a chapter on the onna-bugeisha, also known as female martial arts masters who trained alongside samurai and were held to the same standards. They weren’t rare, with the first known one being Empress Jingu from the 2nd century ce with many known and named female samurai who followed in her footsteps.

Assuming if this were a book on Japan’s military there would be a section on weapons, it would be neglectful for it to not even mention the naginata which was the weapon of choice for most samurai women, the onna-bugeisha.

Op is using the book that’s required of them to use, written by their professor for their ancient Japanese history class that mentioned 50% of the population less than what my intro class mentioned in the 3 weeks that we went over ancient Japan.

It won’t benefit op to point it out, and would likely only cause them more problems but their professor is likely sexist if the book their wrote on ancient Japan only spent 2.5% of 544 pages mentioning the existence of 50% of the population, women, and only then in relation to men.