I found this ''Five Guilty Gear Design + Graphics Documents'' on Archive org :
https://archive.org/details/GGXrd-des...

I didn't really read any of this, just look trough images, This is probably super intresting read if you understand animation and stuff.

If I read correctly this was transled to English by Leo Bruno ''GKK'' (LeoBgkk).

Concept art Faces at 01:52 Are from a Different think, ''Guilty Gear Xrd Visual Book'':
https://archive.org/details/ggxrdvisu...

Background Music: Guilty Gear Xrd Ost ''Jack-a-Dandy''