Here the player can gather and store books, that are earned from fighting Elite Stages in the Campaign.
Once a book is completed, the player can then train certain Heroes depending on the information in the book. For example, if the player has the book Nautical Chart Lv. 1, they can train Admiral's "The Gift of Life", which will increase her Hit Points.
Each book has a necessary path that must be taken to train Heroes. As with Nautical Chart, the player must first train Admiral, then they can train the next hero in the path, which would then be Shadowleaf. Once Shadowleaf is trained (depending on the path taken), the player can either train Admiral again for STR and Armor Penetration, or Shadowleaf again for a Hit Point buff. Each time you train a hero, it will cost you gold and resources. Level 1 books take 10 Book pieces/fragments to make.
Leveling the Academy unlocks a higher level of book research. Meaning a Level 1 Academy can only research Lv. 1 books. Level 2 academy can research Lv. 2 books and so forth.