Ni no Kuni II: Revenant Kingdom - The Prince's Edition

There are 15 manuals you will need to unlock this. None of these are missable. The trophy unlocks when you hand the last book in to the training ground in Evermore:

4 from citizens of Evermore which will be available after completing memory doors of the DLC story. These will appear as quest markers on your town map.

6 from Solosseum Slog completion rewards. You will need to work your way to about battle 27 before you have all the manuals.

5 are in chests in the memory doors:
-The second area of the Little Ring door in the dead end by the exit.
-The second area of Nella's door down the second dead end path.
-The third area of the Cutlery door. There is a staircase that goes to the roof of a building on the right side. Jump across the gap to another roof to find a chest.
-The second area of the Empty Book door in the first dead end.
-The second area of the China Cup door in the dead end near the exit.

Taken from TheBig-BB @truetrophies.com