>>9217043>>9217201>>9217304Here's the concept art of Fauna and a little bit of the rigger's model.
Mori looks like she's wearing a push-up bra, Fauna doesn't, so her cleavage isnt squished together like Mori's.
It looks like a rigger issue with the shading of her breasts to give the perception of depth while leaving her skin a little lighter. This is probably what's bothering you. Riggers can always have a hit or miss when they start creating the live2d models