Great Catastrophe

The Great Collapse, Great Catastrophe, or Collapse of New York is the name given to the event in which a portal opened between the Otherworld and Earth in the city of New York, and works as the premise for the plot of the series.

About
In the night of New Year's Eve of three years ago in an unprecedented disaster of unknown origin, a large hole opened up in the middle of New York City that connected to another realm known as the Alterworld. During the course of that whole night, the city of New York was destroyed and reconstructed as Hellsalem's Lot. This collapse affected both Earth and the Otherworld, and was halted with the raising of a Barrier. From the portal at the center of the city comes a fog from the Alterworld. Transit in and out from the outside world is conducted via the one remaining bridge.

Ever since the creation of HL, the world's attention has been focused on it as a hyper-abnormal city, mixing the Alterworld and this world, and it is also said whoever controls this city will dominate for the next 1,000 years.