I've read that NHK news presenters are also trained to use emotional language/tone in this kind of emergency, so that people would pay a better attention.
There was a significant revision of emergency response in Japan in the past five years.
>In the U.S. news presenters use hyperbolic language and an upset tone about everything.
What? No they don't. You may be confusing news presenters with some parody of the same, or with people like Bill O'Reilly, who are not news presenters, but commentators.
American news presenters, like news presenters almost everywhere, are trained to avoid hyperbole and emotional tone. Although admittedly, the line between news and commentary is getting purposely blurred because news is boring and opinion is engaging.
Now North Korea - they do "hyperbolic language and an upset tone about everything."
There was a significant revision of emergency response in Japan in the past five years.