This is the 5905th most frequent Japanese word.
みゆき
"みゆき" (Miyuki) is a Japanese feminine given name meaning "beauty and happiness" or "snow."
In this context, 'みゆき' once again acts as a proper noun, naming a person who works at the shop.
お店のみゆきはとても親切です。
The Miyuki at the shop is very kind.
In this sentence, 'みゆき' refers to a proper noun, specifically a person's name, 'Miyuki'.
あたらしい小説はみゆきさんが書いたものです。
The new novel was written by Miyuki.
Here, 'みゆき' is used poetically to refer to snowfall or snow scenery, showcasing a figurative meaning.