

I’m on Rakuten Mobile. It’s cheap, but the signal isn’t great outside cities, so I wouldn’t really recommend it unless you’re in a more urban area.
It’s not very reliable compared to big carriers like au or docomo — during peak times, the connection can get quite slow, though it doesn’t completely stop working.
I’m from Japan!
Online glasses shopping is pretty common here too, and I’ve personally used Zoff (https://www.zoff.co.jp/) — they’re affordable, have lots of frame styles, and let you enter your prescription online. They also have a virtual try-on feature on their website, so you can see how the glasses look on your face before buying. Shipping within Japan is fast and reliable.
Another unique option in Japan is Shitsuji Megane eyemirror (https://ec.eyemirror.jp/ ), which translates to “Butler Glasses.” They’re known for collaborating with anime and VTuber franchises, so it’s especially popular among fans of Japanese pop culture. Some of their designs are themed around specific characters or series — very Japan!
(This comment was written with the help of machine translation)