秘ひ中ちゅうの秘ひ

expression, noun

top secret; most confidential

Emphatic expression meaning the most secret of secrets; used for information that is extremely confidential.

• この書しょ類るいは秘ひ中ちゅうの秘ひだから、誰だれにも見みせてはいけない。

  This document is top secret, so you must not show it to anyone.