Hades

A mysterious, mentally disturbed student who claims he is the "Lord of Hades." He conceals his identity with a souvenir mask bought from Guam. In his mind, this world they have fallen into is survival of the fittest and he plans to kill anyone and everyone on the island. He also pressures Arita to become a murderer after he tricks him into killing an innocent girl to protect his secret. His identity was never revealed, even at the end of the manga.