Sorry to say this is not the same. According to [0], the eircode is tied to the address, which Japan has already implemented a 7 digit postal code system. What this new way is trying to do instead is you can get a new digital address, in 7 character alphanumeric character, that uniquely addressed to you. So today you maybe in Tokyo, maybe a year later in Osaka. The postal code of your address changes, but the digital address will still be the same.
[0] https://www.eircode.ie/getting-an-eircode [1] https://en.wikipedia.org/wiki/Postal_codes_in_Japan
Currently the eircode is specific to the residence, unlike Japans current system.
All that's different with Japans new system is that the code will be transferrable whereas Ireland's is not.