This is Ireland's postal code system. There's a small level of privacy built in, specific to an address (many taxi drivers ask for this) and 7 digits long. Web forms use it too, so quite common in normal life.
Surprisingly the postal service, An Post, don't use the postal code as their primary way to direct mail (as far as I understand) .
[0] https://www.eircode.ie/getting-an-eircode [1] https://en.wikipedia.org/wiki/Postal_codes_in_Japan
All that's different with Japans new system is that the code will be transferrable whereas Ireland's is not.
I'm not sure how the delivery system works exactly, but I think they use the eircode? Especially in the countryside there often isn't much more than that. At my previous address the street doesn't even have a name; but post addressed to "my name, town, eircode" got delivered.
Also when the eircode was first introduced it really messed up the delivery, which seems to indicate they're using it?
Sorry I have it the wrong way round, there was earlier confusion which led to the below article and my incorrect understanding.
The system uses the eircode and the postman uses the address. (It makes sense a person would use the street address.)
https://www.irishtimes.com/news/ireland/irish-news/an-post-c...
Addresses are one of those things that “what programmers frequently get wrong about X”.