Is the Kuni face painting exclusively used by the Kuni schools, or they’re used by members of the Kuni family who studies under a different curriculum.

Since your paints are based on the one from your teacher, I don't really see it outside of Kuni Schools, but some of the vassal families may be teaching non-Kuni schools and have face paints.

My understanding is that the Kuni believe that many ghosts cannot identify someone with a painted face as a human, which shields the other humans from their revenge.
"I was slain by a two-legged creature with a red and white face. When I find another one, I will make it rue the day!"

If so, it is both possible that the young Kuni took this belief with him when he transferred over to the other school, or that he left it behind. So I see both options as valid.
Other clans would find it very strange, of course, and if the new school is not concerned with hunting monsters, it would be seen as a bizarre habit, e.g. in a courtier or shugenja.

Thanks guys. I will like to do a test drive of Spooky’s Emma-o Shugenja and thought of using a Kuni for a family but not sure if because he wasn’t attending a Kuni school he was allowed to use their makeup.

26 minutes ago, FelixFenix said:

Thanks guys. I will like to do a test drive of Spooky’s Emma-o Shugenja and thought of using a Kuni for a family but not sure if because he wasn’t attending a Kuni school he was allowed to use their makeup.

The Kuni are not much about brand management. If it works against Tainted creatures, the more adopt it, the better.
The problem is rather all the other people asking behind your back: "Why is he dressing like an insane inquisitor?"

That’s understandable hehehe. Kuni were my first option for playing an Emma-ō shugenja closely followed by a Scorpion.