Eleven subspecies of the White Wagtail (Motacilla alba) are currently recognised and they all have slightly different plumages.
This is the subspecies Motacilla alba lugens which occurs in Eastern Russia and Japan.
The black eyestripe is distinct.
First winter birds often show a yellowish face (2nd, 3rd & 4th photo).

1st, 2nd & 3rd photo: Shirakawago, Gifu Prefecture, Japan, 26 September 2018
4th & 5th photo: Kyoto, Japan, 3 October 2018