As of January 1, 2022, the JPO abolished the requirement for seals or signatures on procedural documents and the regulations for proving documents to be submitted so as to verify such seals or signatures, with some exceptions (procedures in which the damage caused by falsifying documents is significant—e.g., transfer of right). With this revision, it was no longer necessary to include a seal or signature on a Power of Attorney (POA).
https://www.jpo.go.jp/e/system/laws/rule/other/signature.html
Although the POA to be filed no longer needs a seal or signature, it was still necessary to file the original document with the JPO, rather than a copy.
Given this situation, on September 26, 2022, the JPO announced that the ministerial ordinance has been revised to allow applicants to file a copy of the POA. This revision will make the process more convenient.
https://www.jpo.go.jp/system/process/shutugan/madoguchi/info/dairiken_shomei.html
(only in Japanese)
Please note that there is no change in the filing method—that is, it is necessary to a hard copy of the POA to the JPO directly or send it by mail. In other words, it is still necessary for the actual digitization of the document to be carried out by the JPO. The JPO states that online filing of the POA is still under consideration.