Because of that trash king. They were probably given to the other heroes.
Geez, they left me out to die.
"Although magic books are a bother, one could learn 10 spells in a single month with dedicated studying."
So, 1 spell with the crystal ball and around 3 spells per magic book; though I still can't read it yet. No, since she said a month maybe there's something more to it.
"My apologies."
"No no, these magic books are more than enough.