These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Despite the greater magnitude, however, this one's epicenter was 130 kilometers offshore, and has thus had far fewer casualties (though still far too many). It'd be hard to have more — the earthquake in Tokyo Magnitude 8.0 explicitly had more casualties than any in Japan's history.
The quake happened far away from Tokyo and the aftershocks only caused minor damage, but even they were still the strongest earthquake to affect Tokyo since the one in 1923.
Nightmare Fuel: If you live where a major earthquake is expected, this could very well cause some mental discomfort.
Shocking Swerve: Mirai's descent into apparent hallucinations after Yuuki's sudden death was not particularly well-received by a portion of the viewership, as it marked a shift in tone from objective and realistic to either supernatural or subjective (Mirai's POV). Yuuki's death itself also appears to be a case of this at first; had Yuuki suffered a cerebral hemorrhage as suggested by fans, however, his condition would likely have deteriorated that quickly.
What an Idiot: Kento risks his life to save a mass-produced reconnaissance robot.
Woolseyism: In the Japanese version, Yuuki and Itsuki call Mirai the phone alien. The English dub tweaks it around to make it sound more alien-like, having them refer to her as the "Cell phonian," which is much more creative and sounds just like something a seven or eight year old kid would come up with. It's the same thing with "Frogworlder" and "Sergeant Snack Time."