Prefacing that Japan is not open to foreign tourists currently, but this post is for future reference. The coronavirus pandemic affected Japan heavily, like many other regions in the world, but along with it came the rising trend of remote work. In response, several Shinkansen bullet train operators in Japan started providing a remote work train service.
For example, the Tohoku, Joetsu, and Hokuriku Shinkansen trains, which service Kanazawa, Niigata, and the Tohoku region of Japan started an office car service. In the office car, passengers are explicitly allowed to make phone calls and join online meetings from the train, which are activities normally discouraged on trains in general in Japan. There’s no extra charge for this service, you just need to explicitly reserve a special car on the train. You should be able to reserve this with the various JR Passes as well, either the nationwide pass or the JR East Pass. I haven’t ridden this myself, but you can read more details here: https://english.kyodonews.net/news/2021/11/e3350c504173-jr-east-launches-bullet-train-office-cars-amid-telework-demand.html
The Tokaido Shinkansen, which services Tokyo, Nagoya, Kyoto and Osaka, now have a special train as well called the S Work train. You can reserve that train online using the smart EX service, and can even load the Shinkansen ticket to your Suica or equivalent IC card as well! You might be able to reserve these with the JR pass as well, it should be car 7 on the Tokaido Shinkansen.
Using the smart EX service, you can see that the price for the S Work car is the same price as a reserved seat.
What I have found is that the services on the S Work cars are slightly inconsistent. Sometimes there is power at every seat, sometimes only the windows. Sometimes the WiFi allows 90 minute sessions instead of the usual 30 minutes and has faster bandwidth than the usual low cap. So I’m not entirely sure what the guaranteed service points are. One plus is that for some reason, I’ve found that certain sites through VPN don’t work on the normal Shinkansen WiFi like my corporate Github Enterprise, whereas it works on the S Work cars. It’s possible that this service extends to Hiroshima on the Sanyo Shinkansen as well, but I haven’t checked.
In summary, reserving a remote work car can ensure that you are respecting manners while riding the train, and also ensuring power outlet access and possibly better internet.