Shadow is the first chapter of the first Durarara!! light novel.
Members of the chat room discuss the Dollars and an urban legend called the Black Rider. One member of the chat claims the Black Rider is headless under its helmet. The other two members think this claim is far-fetched.
In Tokyo, a group of thugs are attacked by the Black Rider. When the Rider is hit by the thugs' van and its helmet is knocked off, it is revealed that the Black Rider has no head.