Thank you so much! <3

It's a shader problem. I go over this in the guide linked in my signature. At this time there does not appear to be a shader in Unity that is as good as CC3's internal shader for hair, but you can come pretty close (close enough to satisfy, I think).

If Reallusion would make us a hair shader for Unity they could sell it on the asset store for a good profit...

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CC3 & Daz Tricks | CC3 to Unity workflow

FWIW, I have yet to find a combinations of settings and shaders to make CC3-exported hair look reasonably good in Unity! Then again, it could be that the hair models in CC3 are themselves bad to begin with...

The hair looks great inside Character Creator but after importing it to Unity it looks terrible, any ideas? It clearly has to do with normals etc, but I tried using a two-sided shader and still looks terrible.
The first pic shows the model inside Unity, the second inside Character Creator 3 and the third using a two-sided shader.

Terrible transparency issues inside Unity.


the hair looking pretty decent inside character creator.


Two-sided shader applied with questionable results.