expression
well-known to those in the know; known to connoisseurs
A set phrase used to describe something that is highly regarded or famous within a specific, often niche, group, but not widely known to the general public. Often used to praise hidden gems, such as restaurants, products, or experts.
このラーメン屋は知る人ぞ知る名店だ。
This ramen shop is a famous establishment known to those in the know.
彼は知る人ぞ知る腕利きの職人です。
He is a skilled craftsman known to connoisseurs.