The app itself has alerts so I'm surprised people are using Twitter to get it's alerts. I don't use Twitter, but I didn't know that was a thing. NERV is the fastest-alerting app I've found on Android for quakes here. Good on them, though, for better use of their money and getting off that hellhole.

As others have mentioned, Twitter is huge in Japan. Almost no small businesses have websites; they market and show availability etc. through Insta, FB, and twitter