A Digital Artbook featuring artwork and the original soundtrack of Fate/Samurai Remnant.
You can access the content from the Title Screen once you apply this DLC.

Contains more than 180 pieces of visual materials such as character designs and reference sheets, allowing you to take a closer look at the game's universe. The soundtrack features all 89 in-game tracks, including the theme song.

Note:
Some of the materials featured in the content are closely tied to important story elements. Please keep that in mind before viewing the content.
The Digital Deluxe Edition that includes this content is also available for purchase. Please avoid making redundant purchases.

More details on the official game page of Fate/Samurai Remnant Digital Artbook & Soundtrack ...