On February 2, 2024, the Japan Patent Office (JPO) announced that it will launch a patent application non-disclosure system on May 1, 2024.
f a patent application contains an invention that is likely to endanger the security of the nation and its people by making the specification, etc. of the application public, the JPO will withhold patent procedures such as application publication, patent examiner's decision, and decision of refusal by designating a preservation designation after a preservation examination.

Examination is conducted in two stages: examination by the JPO (primary examination) and provisional examination by the Cabinet Office (secondary examination).
If the applicant submits a written request to submit the application for provisional examination, the application will be subject to provisional examination in principle.

Japan Patent Office:
https://www.jpo.go.jp/system/patent/shutugan/hikokai/index.html