na-adjective, noun which may take the genitive case particle 'no', noun
Describes information, documents, or matters kept strictly confidential, often in official or organizational contexts.
This document is treated as top secret.
極秘情報が外部に漏れた。
Top-secret information was leaked to the outside.
The plan was kept top secret.
The development of the new product is being carried out in secret.
This document is being treated as top secret.
classified information; top secret