I can't make out the fourth character on that ero book, but I think you can guess what it represents.

... Why is it always the subject of the book, themselves, who finds such a book?

NWSiaCB said:

I can't make out the fourth character on that ero book, but I think you can guess what it represents.

... Why is it always the subject of the book, themselves, who finds such a book?

Because it would not be funny?