Free Wifi spot in Japan is the world's lowest level. And you will not be able to buy a SIM card easily in Japan. So I will introduce the SIM for travelers. ※This article is not intended to promote the use of the terminal without the Technical Conformity Mark.
Do you know the b-mobile? b-mobile is a MVNO(Mobile Virtual Network Operator) of NTT DOCOMO. b-mobile is selling pre-paid SIM for mobile data only. It is "b-mobile VISITOR SIM" and "b-mobile3G･4G 1GB Prepaid". I will introduce the b-mobile3G · 4G 1GB Prepaid here.
This can be used for 30 days 3G and LTE to 1GB. It will expire when you use up 1GB. Even if you live overseas, then you can import from Amazon.co.jp this. And this can not be purchased at electronics stores or carrier shop How to activate and APN settings.「Activation & Setup」 You should check the following Article.「Smartphone that can be used LTE in Japan」 Check the column of NTT DOCOMO.