On September 20, 2023, the JPO announced that all applications to be submitted to the Office that are not currently eligible for electronic filing will be able to file electronically in the future.
The new system will be released after January 2024, pending the enforcement of relevant laws and regulations.

As a result, all application documents will be able to be filed electronically using Internet application software.
However, it should be noted that electronic applications for PCT international applications differ from domestic procedures in some respects, such as the fact that signatures created by the Digital Agency GPKI electronic signature application cannot be used.

Japan Patent Office：
https://www.jpo.go.jp/system/laws/sesaku/shinsei_digitalize.html
Electronic Special Application for PCT International Applications：
https://www.jpo.go.jp/system/patent/pct/tetuzuki/pct_digitalize.html#1