Well, she doesn't come with a "book skill" per se. The pre-learned skills and Skill Books are different from the skills in the Hero Academy, which have to be learned separately.
The example I used for the Skill Books is more in regards to being able to use any level skill book, as you find it, to replace any skill that's already learned. The difference between the Academy and the Skill Books is that you have the option to specify which skill(s) gets replaced with the Academy skills, whereas Skill Book placement is entirely random.