Data only, no calls. You need to view ads and complete a survey to get this for free.
Good insurance policy as it gives access to Google Maps/WhatsApp in case a group member gets separated from the group.
Further details can be found on the Prepaid Data SIM Wikia: www.prepaid-data-sim-card.wikia.com/wiki/Japan#Japan_Welcome…
You can pick up these SIMs for free here at various airports, however you must register online in advance.
Data speeds limited to 128kb/s. SIM valid for 15 days.
Tell me how it goes :)
When staying at most Airbnb, they have portable hotspots. They ended up being much faster than a 4G sim I bought specifically for use in Japan.