From the introduction:
It is Japan in the year 2014, but it’d be foolish to say that the world is like the one you know. For one thing, this world has had multiple advances in technology in fields that are only dreamed of. Data and matter becoming interchangeable, artificial intelligences and fully-functioning androids capable of independent thought... however, it is these wonders that also bring the chief threats of the world. The androids were created by an evil man who drove them into a species-wide crusade against Humanity, while data-based entities known as Bugster are emerging and attempting to bridge the gap between reality and the digital world. Meanwhile, a world in a parallel reality already destroyed and howling from their own abuses of technology and their home eyes the planet Earth greedily, more than willing to change this blue ball into something more comfortable for their kind. No matter the threat, this world is also different from the one you know in another way: It will bring about Heroes, willing and able to use the powers of those who would bring the planet harm against them. Heroes who are willing to be the fangs for the fangless and defend those who are trying to live honestly. Heroes known as Kamen Riders.