Japanese paperwork is a chain: each step unlocks the next. Get the order right and most of it is done within a fortnight.
Sort out data before you fly. You'll need maps, translation and messaging from the airport onward, long before you can sign a Japanese phone contract. A prepaid eSIM covers the gap. Phone and internet guide
Find your address, then register it within 14 days. If you're allowed to stay in Japan for more than three months, you must register your address at your city or ward office within 14 days of moving in. Bring your residence card.
Your My Number comes from that registration. Japan issues My Numbers to people on the resident register, so it follows from the step above. How My Number works
Open a bank account and fund it. Bank requirements vary; check what yours asks for before you go. Once it's open, you can send money from home with a transfer service. Money guide
Apply for your first credit card. With a residence card and an address, you can start. Expect a modest limit at first. Which cards newcomers start with
Moving house later? The same 14-day rule applies to registering your new address.
What to have ready on day one
Airalo
eSIM
Prepaid travel eSIMs you can install before you fly, so you have data the moment you land.