What should I do/know when I arrive at the airport?

Narita Airport is reasonably easy to navigate, staff have a good understanding of english if you are lost or have questions. ATM's are available but not everywhere (or accepting of all cards) so it is recommended to have cash on you. Rail access is via the Narita Sky Access line, Keisei line and JR line.
Uber is only available as Uber Black and both this and taxi's are rather expensive to travel around in. If you are looking for a shuttle service a number of these optons are available at the airport (Known as airport "limousine") or booking on websites such as Klook.
Free WiFI is available everywhere around tokyo including on some of the trains.
The taxi service also has an app known as 'JapanTaxi' which connects to a number of local companies.

What's different from other countries/cities?

Convience store such as 7/11 or Family Mart have great lunch boxes.

I need a SIM card

Mobal, Sakura Mobile, Sim Card Geek or Klook all offer short term SIM cards (note that some do not come with Voice Calling Enabled). Longer term you can look at Softbank or Docomo who have recently allowed tourists to purchase SIM cards/plans. Alternatively you may get higher data cap with a Pocket WiFi - Japan-Wireless is recommended for a truly unlimited data plan.

Where can I book a hotel / apartment?

Short Term : Agoda, Booking.com or AirBnB (Check that the AirBnB is correctly registered)
Long Term : tokyocityapartments.net

Where should I stay / live?

Ebisu / Nakameguro are residential area but with plenty of restaurants and bars, in the expensive side
Ikebukuro is slightly far from the city, but connected with the JR with easy change

I need a bank account / debit card

Japan Post and Shinsei bank are your best options as a tourist or visitor, however both require you to have a resident card to register an account. JP Post requires you to have your passport and resident card as well as proof of address, it is best to visit a local branch to get everything set up.

How to go from A to B?

Tokyo has an amazing public transport system that is fully integrated into Google Maps. Trains are almost always on time and run from most stations every 10-15 minutes (in some cases quicker). A large majority of Tokyo can be travelled via Train. It is recommended to get a Pasmo or Suica Card to save carrying cash. These cards can also be used to pay for goods and services at a number of convinience stores, arcades, coffee shops and more.

Coffee shops / Coworking to work from

Yahoo Lodge in Akasaka ( goo.gl/maps/4fYD3JP9rapnpvZN7 ) and AWS Loft ( goo.gl/maps/as8D6YUSUjL4vaRPA ) in Naka meguro are made for work, great and free.
Excelsior Caffé @ Nihombashi goo.gl/maps/6gkcLR9PrCTzo8WB9
Coworking spaces with daily pass: Hive Jinnan in Shibuya, Ginza Hub, Shimbashi Key Station and 1/3rd Life in Akihabara

Unique things I can only do/buy here?

Japan is known for its crazy and delicious Kit Kat flavours. Major cities also have their own unique flavours (Such as Tokyo's current Tokyo x Banana Kit Kat).

A number of shoe brands such as Nike or Adidas also have Japan exclusive shoes which are available at most major shoe outlets (such as Shoe Mart)

Make sure to visit a drug store for cosmetics Bic Camera to shop electronics with great value. Don Quijote a huge shop up to 8 stories with literrally everything.

New York Bar @ Shinjuku (at the top of Park Hyatt Hotel) has the best view of the city. Dress properly, and go enjoy their cocktail and enjoy the live band. There is a 2500 cover charge you can avoid by leaving before the live show starts 8pm on weekdays.

Who should you thanks for those informations?

Found some outdated informations? An other "FAQ" section is needed? Just add it in the crowdsourced Google Spreadsheet ❤️ docs.google.com/spreadsheets/d/1-Lut4zmeDw9z-ikRJPH1nrmXGqt6rYDWGraFYUGnPUk/edit#gid=913136982