Mr Ishimori said NERV is heavily influenced by hit anime TV show Neon Genesis Evangelion, which is set in a post-apocalyptic world after half of the human population has been wiped out.

The account’s name “special service agency NERV” is a nod to an organisation in the show that issues alerts about threats to humankind.

“I created NERV as a parody account because Twitter was getting popular at the time,” Mr Ishimori tells the BBC.

“It started as my programming hobby to post automated tweets about weather alerts using the Japan Meteorological Agency data.”

At the time, the account only had around 300 followers.

But then in 2011, Japan’s most powerful earthquake on record struck.

Best known for triggering a tsunami that caused a nuclear accident in Fukushima, the quake also caused great loss of life in his hometown Ishinomaki in Miyagi in the north-east of the country.

For four days, Mr Ishimori was unable to contact his family. “To be honest, I thought they must be dead,” he recalls. He later found out that while his immediate family was safe, one of his aunts had died.

“I realised we needed to have other ways – not just TV and radio – to communicate disaster information,” he says, as TV became useless during power cuts.

He started posting about earthquakes, and as Japan experienced more natural disasters, the account added hundreds of thousands of new followers.