This is the first time I have encountered such a problem with my characters. I know we're all familiar with the pestering neck seam that can spring up when face and body textures get changed, but this is something entirely new to me. Not only is there a clearly visible gap in the back, but from the front there is an overlapping "flap" that almost looks like he's wearing a mask of some sort. I've only ever seen it on this custom NPC of mine and no others. The usual high collared clothing, or wearing an amulet doesn't seem to cover it up, either. I was afraid changing his height in the Creation Kit is what caused the problem, but I shrunk him back down to the Bosmer base height and it was still present. The only custom items on him are his hair (which has never caused any problems with either NPCs or PCs), and his body texture which is present on all male NPCs in-game and none of them have this issue. I'm at the end of my list for probable causes here, does anyone have an idea?