Zankyou no Terror tells the story of Nine and Twelve, the two boys behind the masked figures of Sphinx. Unable to stop the mass panic quickly spreading through the city and desperate for any leads in their investigation, the police struggle to act effectively against these terrorists, with Detective Kenjirou Shibazaki caught in the middle of it all. In it, two teenage boys who identify themselves only as 'Sphinx' directly challenge the police, threatening to cause destruction and mayhem across Tokyo.

The public are clueless-until, six months later, a strange video makes its way onto the internet. The government is shattered by their inability to act, and the police are left frantically searching for ways to crack down the perpetrators.

Painted in red, the word 'VON' is all that is left behind after a terrorist attack on a nuclear facility in Japan.