門もん外がい不ふ出しゅつ

noun, noun which may take the genitive case particle 'no'

never taken out of the premises; kept strictly within the family/group; not for public viewing

Used for treasured items, documents, or secrets that are never allowed to leave a place or be shown to outsiders. Often appears in the pattern 門外不出の〜.

• この絵えは門もん外がい不ふ出しゅつの