A “grace period” is a specified period of time before an application has been filed, and during which time the invention could be disclosed through various means without its novelty being lost (Japanese Patent Law Article 30).
The disclosure within the grace period will not be deemed as prior art of the claimed invention.
The grace period is within 1 year prior to the filing date of a PCT application, or Japanese patent application with (or without) a claim of the priority under the Paris Convention.
The PCT applicant should file a request for a novelty grace period at the time of Japanese national phase entry (the request can be omitted if a declaration as to non-prejudicial disclosures or exceptions to lack of novelty has been done at the international phase) and submit a certificate of the disclosure within 30 days from filing Japanese translation.
(If the disclosure is against the intention of the applicant (e.g., disclosure by breach of non-disclosure agreement), the request and certificate are not required.)