mcrw00

Wife (JP national) and I are planning a trip to Japan next month. The MOFA website makes very clear that all arrivals will need a smartphone in order to report their status during the quarantine period. Would purchasing JP sims for our US smartphones *after* clearing airport immigration create any issues?

JapanFlyerT

Shouldn't be a problem. I had the same question (in July) and asked the immigration office of KIX and they confirmed airport wifi was sufficient (though slow). That said, my teenage son actually had help from one of the officials who had him link to her hotspot since the airport wifi to speed up the process. My other son returned in September, also without a J SIM in hand. Having the apps downloaded to your phone prior to departure is a good idea though. You will need a local phone number.

mongobot

I recently entered at NRT without a Japanese SIM installed and had no problems. The potential issue seems to be when you are asked to confirm that you can receive communications from MOFA.
That is, while going through the arrival process, at one of the stations I had to show that I received a test email to the address I had provided. The agent sent an email and once received, I had to show it to them. I had connected to free WiFi at NRT and the email showed up in less than 30 seconds.

CPH-Flyer

In Narita the challenge with WiFi could be that some of the stations are placed in the normally no passenger access underbelly of the terminal buildings, I don't know how well they are covered with public WiFi.

The flow in Haneda is all in the passenger areas so it should be better covered.

seigex

A suggestion, if you plan on buying a SIM while you're there anyway, is to sign up for Google Fi with bring your own phone on a flexible plan. It's $20/mo, they will send you a sim card in a couple days, and you pay $10/gb with a max out of pocket $80 for the month ($20 for account, $10/gb but they only charge you for the first 6, and you get up to 15GB. Your internet works in 170+ countries, and you will have a local US phone number.

If you change your SIM on your flight, you'll have internet the second you land, and once you're back in the US, just swap your SIM back and suspend your Google Fi account until you get back. I've used Google Fi for a few years, and it's nice having data no matter which country you land in, on layovers etc.

THECLIPPERS

WiFi at Haneda was fine. There is no way to buy a sim if you are going to a government quarantine hotel as you won't have access to any stores.