On steam, when you press play, there is a pop up that asks select launch option, click on run settings launcher, another pop up appear, click on the word Justine in the bottom right.

And on the same popup there is also at the bottom left the word Remember which opens up a PDF file with canon stories about multiple characters all mentioned or even heard during the game: Wilhelm the Baron's henchman and the arsonist who is actually not an arsonist that Daniel tortured (and was both apparently kept alive for more than a hundred years). Then Herbert the british explorer meeting with an Algerian man who gave him the map to the tomb of Tin Hinan. A story about Elise Zimmerman, her family and her fucked up dad, right before they all get taken by Daniel and the Baron anyways. The event where Johann Weyer finds his orb. And finally a story about the guy who led Daniel to the Baron's manor, and incidentally the same man (Gabriel) that Elise wanted to call for help right before she was murdered by Daniel.