Each chapter contains some extra artwork for it. One for the start, one for the end.
They have a random chance to appear on the title screen after completing the chapter.
This chapter gives the player one of the many Remnants, items that buff characters but also provide an additional story.
As of writing this, there is no official published volume 3 of the NieR Re[in]carnation soundtrack, so below are some rips of music from the chapter.
[ Lost Archives IV ]