Rent Mobile WiFi or Simi Card in Tokyo
A hint: if you plan to spend the day exploring Tokyo, buy an Odakyu Tokyo Metro Pass [小田急東京メトロパス] for 900 yen at Komae station. This covers a round-trip into the city, plus unlimited use for the day of the Tokyo Metro (which is one of the two major subway networks in Tokyo). As long as you plan carefully so that you don’t use the lines that are not included, such as JR and the Toei subway, you will save a fair bit of money. Second hint: we strongly recommend buying a data SIM card before arriving in Japan, as there is little free WiFi about. We were very happy with the China Unicom Japan 7 Days 5GB Data SIM, which can be had for about USD18 online (including shipping). Third hint: the Sanwa supermarket near Komae station has half-price sushi, sashimi and other ready-to-eat stuff between 21:00 and 23:00, so you can stock up for the next day.”
In Tokyo free wifi is difficult to find and finding someone who can help you in English can be rare. I wouldn't recommend relying on free wifi to help you find Komae station. When you land at the airport in Tokyo fortunately there is tourist wifi available but if you don't prepare in advance the apartment address and train route then this can make arriving very stressful for you and for the staff waiting to meet you at Komae station.
Free Wifi can be found at Shinjuku station and also at the tourist centre at Shibuya station.
To help with sightseeing I recommend buying a tourist internet data sim card. This can be found at a vending machine at the airport and also at large electronic appliance stories such as 'BIC Camera' in Shinjuku, Shibuya etc.