Wait, so you mean if you stick the nail on her head, she becomes human immediately?
We have a similar creature here in the Philippines. They're called White Lady (normally the "good" ones) and the Black Lady (really evil ones). Yeah, the names are pretty common but that's how they're called.
Anyway, the White Lady isn't always good. There's this famous street here called Balete Drive where numerous car accidents are caused because of a lady who crosses the street just as the car passes by and survivors all claim that they "hit" her but there always is no one else except them.