If you (or anyone else) has to travel to Japan I endorse https://www.rentafonejapan.com/ - they will have the phone or cell modem delivered to your hotel and you can drop it to the reception or in a mail delivery box on your way to the airport.
They delivered it to my hotel and it was easy to set things up.
As another example even though > 40% of users don't have a landline more often than not you can not call a Japanese toll free number (0120) from a cellphone.
There's also the issue that unlike the USA where you can't tell from the phone number if it's a cellphone or a landline, in Japan you can. Cellphone numbers start with 070, 080, or 090 where as landlines start with different prefixes. Because of this you're judged based on your number. A person or company without a landline is judged to be less trust worthy than one with. Oh, and landlines require $700 to start (though that may have been finally fixed)