Pocket WiFi

Pocket WiFi
This is the pocket WiFi that I used on our last trip.
You can rent pocket devices before you go (e.g. HIS in Honolulu), or use service like iVideo where it is delivered to your hotel on arrival, and you drop it off using the prepaid mailer into the mailbox at the airport. All of this worked flawlessly for us, and it was less expensive that renting it in the U.S.

The most difficult decision is deciding whether you need a mobile WiFi or not.
If you have a T-Mobile phone, you have unlimited data in Japan (voice calls are charged international roaming -- better off using VOIP, Hangouts, or Google Voice if you can). It is not the highest speed (3G advertised if I remember correctly), but in practice, I had 4G much of the time there. On a previous trip, I did pay extra for unlimited high speed in order to use tethering for other devices. I can't say that I noticed a big difference in speed, except it added tethering.

In distant areas of Japan, the mobile WiFi did lose signal sometimes (especially I think on fast trains where picking up cell towers can be a challenge) and I'm thinking the cell phone did a little better?
Note that with iVideo or similar, you have a choice of different devices and carriers -- some are better in cities, and some have wider range than others, so you can tailor your choice (and cost) to what your needs might be. Monthly cost ranges for $29 to $36.
https://www.ivideo.com.tw/english/japanwifirental

Also, note that most of the hotels we stayed in had free Handy cell phones docked in the rooms for guests to carry and use. We didn't test it out, but it sounds like a great idea. You just won't have it traveling between cities, and it has a proprietary charging connection in your room.
https://www.japantimes.co.jp/life/2017/06/22/travel/smartphones-allow-guests-stay-connected/
https://www.cnet.com/news/handy-phone-gives-travelers-free-data/

In addition, there are more and more free WiFi hotspots in Japan. You can use apps by Softbank and NTT, and there is free WiFi in major JR rail stations and on shinkansen trains.
https://piece-of-japan.com/directory/wifi/jr-east-free-wifi.html
https://www.japan-rail-pass.com/japan-by-rail/travel-tips/free-wifi-shinkansen

What has been your experience with phone and internet in Japan?

[link, phone, internet, communication, access, JT]