In Chapter 2 "Pursing the Truth", in the prison second screen, go into Look mode. There should be an inscription on the side of one of the pillars. Read it and there should be writing that gives you a code. When you complete Chapter 2 and go back to Elendia, talk to Claude the Dryad in the first room of the magic guild. He will ask you to input the code (Left, Down, A, Up, B). Afterwards, he will thank you by giving you the Item Manual, which can be checked out in the "Extra Content" section of the main menu screen. The Item Manual tells you about all of the items that you have collected thus far, as well as allow you to see what skills each has to offer to every character.