Raised in an orphanage after witnessing his sister's suicide, Satsuki Kakeru's life has already been dark and cruel enough. However, when he and his friend Yuka are thrown into a alternate dimension called the Red Night, it takes a gruesome turn from bad to horrific. Now, trapped flickering between our world and the Red, Kakeru quickly discovers that he and Yuka are not alone, and that, together with the other so-called 'fragments,' they must defeat the malevolent entities known as the Black Knights. Facing monsters from beyond imagination, at the center of a deadly hunt, Kakeru's only chance of saving their lives now hinges on finding the power buried within himself!