Ten years ago, an enigmatic phenomenon called Hell's Gate suddenly appeared in Tokyo, shrouding the city in darkness and hiding the stars. However, it also led to the emergence of new stars representing people with otherworldly abilities, known as Contractors. These amoral beings are lethal in every sense of the word but often go unnoticed by the general public, including high schooler Kana Shinoh, who remains unaware of the rumors surrounding Hell's Gate.
However, everything changes when Kana encounters her supposedly deceased father in the streets. Obsessed with the idea that he's still alive, she attracts dangerous attention. Luckily, Hei, Tokyo's most wanted Contractor, comes to her rescue, albeit with his trademark lack of sympathy. Hei agrees to protect Kana and help her search for her father, but can she trust the infamous Black Reaper with her life?
