Hey gramps, sorry to interrupt your get together but I need some retard newfag help pronto.
What would cause my model to have a fucking neckseem? 
I've been turning in circle for like 2 days now trying to fix it and I feel like it's something super simple that I missed.
The exact same material is put on both my head and body yet they don't light up in the same way at all under different lights, I even tried with the model straight from booth to make sure it wasn't any of my amateur work that fucked anything up and surprise, I have the same problem.
Anything I can do except Atlasing? I've been trying for a while and I don't think I'm there yet, I need a quick fix for now. 

Pic related is one of the most egregious example, it looks different under every light source and even looks fine under some. Shader is latest version of liltoon.
Cheers