As someone who professionally writes code that has to ingest mail carrier invoices/other CSVs, this is probably the worst I've seen, but some of the files I've dealt with were ... let's say comparably frustrating.

Mostly it's because mail carriers tend to write these files for humans/accountants to read and audit, so they'll pull shit like putting in a whole differently-formatted chart above the actual CSV formatted table, or sending us password-protected, encrypted XSLX files that we need a human to decrypt using Excel before we can ingest it with our data tools.

Leave it to Japan to take it to the extreme by making their software in a fully bespoke way.