When you are in Japan, I always hope you are staying in safe, and have fun (no crime like wall painting, we are strongly angry for such rude foreign visitors).
However it is also true that we have disasters in many places.
In here Japan, we do not speak English, generally. Writing is better — no capitals, no slangs, no 2 terms words especially starting “get”. You should better to write letters like “Times New Roman” font with writing like text books. Or using your phone’s memo pad.
1) Being safe, I recommend to buy Tourist SIMs. Please do not stingy with buying it. It is not so much expensive, I had bought for myself.
See also: Tourist SIM in Japan
2) Turn your phone’s disaster notification on.
They may send you alert by noise in Japan. This is the very what I got recently, due to the heavy rain.
・Japan Meteorological Agency
We Japanese often check informations through TV news and Radio.
There are free (and safe) applications but mainly in Japanese. If your smartphone has “FM” use it, you can find channels.
I have not catching radios by Foreign languages.
If you do not understand Japanese, probably you can see what they are with seeing pictures. Staying your hotel to see, but there are some online news.
Guess the most easiest thing to see is 日テレNews24, search in “News 24” to find.
“00000Japan” aka five 0s Japan, is the collocation of telecommunication companies.
You will see “00000Japan” in free WiFi. It is not secured.
When you see this WiFi if you are in safe area, it is a fake.
Anyway, please do not stingy with buying VPNs.
Have Fun! and be safe!