Japan does things in its own way, in its own time, and according to its own understanding, which isn't always the same as anybody else's.
Take names. I am ヨーマンズ クレラ, which roughly reads Youmanzu Kurera, since Japanese simply cannot do Claire and barely manages Klara. It does Youmans just fine, though, and since I'd normally be called Ms. Youmans in English, as I am old and dignified, I am very happy to be Youmans-san.
But in the Meiji-era, few people had surnames. Even the upper classes barely had them, mostly using clan affiliations on official records only. My main characters have the family name of Maeda, because they are samurai and can trace their ancestry back to Sugawara Michizane, though through a great many twists and turns. They keep track of the connection though, because it's an illustrious one and sometimes that is useful. Anyway, comprehensive and accurate records are very important!
When the Westerners came, all of them with surnames except the very highest born who had titles instead, Japan decided everybody needed to adopt a surname and reorganize their family registers, the most official of which were kept by local Temples, then Shrines and, later, the civil authorities.
For most people, it was easy to make something up. They used an occupational name, a place name, or picked something that signified good fortune, sometimes at the suggestion of the Shrine priests. For others, as we see in The Shadows of War, it was a little harder as the characters in question wanted names that spoke to them and signified their personal heritage.
But Japan still keeps track in what strikes me as rather odd ways sometimes. Yesterday, I received Mystery Mail from JP Bank. What it wanted, I discovered, was to update my zairyu, or resident, card, and to discover what I do with the money that comes into and goes out of my account. It had a QR code so I could fill out the form from my phone and a website where I could do it on line.
And now, an hour later, I am all up to date on bank record-keeping: another mysterious adventure of everyday life in Japan.