Before you start

A Certificate of Eligibility obtained by your employer or sponsor before the visa application, for most work statuses
A visa issued by a Japanese embassy or consulate
A passport valid well beyond the intended stay
An address in Yokohama, and knowledge of which ward it falls in

Step-by-step

1
Receive your residence card at the airport
For medium and long-term stays the zairyū card is issued on landing at Haneda or Narita. Check the name spelling, status of residence and period of stay immediately — corrections are far easier at the counter than afterwards.
In personWho: YouOn arrival
2
Confirm which ward your address is in before you travel to an office
Yokohama has eighteen wards and they are large. Your ward is determined by the address, not by the nearest station or the postal town. Confirm it from the city website or your lease rather than guessing — turning up at the wrong ward office costs a day against a legal deadline.
OnlineWho: You
3
Register your address within fourteen days
Take your residence card and passport to the correct ward office. This produces the jūminhyō residence certificate and starts your My Number. Fourteen days is a legal deadline, not a guideline, and everything else waits behind it.
In personWho: YouWithin 14 days of moving in
4
Enrol in health insurance and pension at the same visit
If your employer runs shakai hoken they handle it. If not, enrol in National Health Insurance and the National Pension at the ward office while you are there — both are compulsory and one appointment saves a second trip.
In personWho: YouSame visit
5
Apply for the My Number card, not just the number
The number arrives by post; the physical card is applied for separately. It is increasingly used as identification, for online tax filing, and now functions as your health insurance card.
OnlineWho: You
6
Carry the residence card, and report every move within fourteen days
Japanese law requires foreign residents to carry the card at all times. Moving — including between two Yokohama wards — means a move-out notification at the old ward and a move-in registration at the new one, both within fourteen days.
In personWho: You

Documents you’ll need

Passport with the visa
Certificate of Eligibility, if issued
Residence card
Proof of your Yokohama address
Employment contract, for status-related procedures
Passport photographs to Japanese specification

Things most newcomers don’t know

Working in Tokyo does not make you administratively Tokyo's, and this catches people constantly.

Yokohama is a separate municipality in a separate prefecture. Your ward office, residence tax, National Health Insurance premiums, school zoning and even rubbish separation rules are Yokohama's, and the immigration office covering Kanagawa residents is the Yokohama district office rather than one of Tokyo's. People who describe themselves as living in Tokyo because that is where they work turn up at the wrong counter and lose a day against a fourteen-day legal deadline.

Source: Yokohama City

Eighteen wards is more than any other Japanese city, and they are not small.

Yokohama's wards stretch from the waterfront to hills twenty kilometres inland, and the ward covering your address is not always the one you would guess from the nearest station name. It determines where you register, which schools you are zoned for, and where every subsequent municipal procedure happens. Check the address against the city's ward lookup before you set out.

Source: Yokohama City

The Highly Skilled Professional points system is worth checking before accepting a standard status.

Japan scores education, income, age and Japanese ability, and clearing the threshold brings a five-year period of stay, permanent residence in as little as one to three years rather than ten, and easier family arrangements. Many eligible people never calculate their score because an employer applied for an ordinary work status by default. It is worth ten minutes with the official points table.

Source: Immigration Services Agency

You must carry the residence card, and this is enforced.

Japanese law requires foreign residents to carry the zairyū card at all times, and police checks do happen — more often near stations and on bicycles. It is not adversarial and the interaction is short if you have the card. Leaving it at home with your passport, which is the instinct from many countries, is the mistake.

Source: Immigration Services Agency

Common mistakes to avoid

Assuming your administration is Tokyo's because your job is.
Turning up at the wrong one of Yokohama's eighteen ward offices.
Missing the fourteen-day registration deadline and blocking everything behind it.
Not filing a move-out notification when relocating between two Yokohama wards.
Accepting a standard work status without checking your Highly Skilled Professional score.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.