A species that has the ability to hunt mutants, a perennial species. One day, they suddenly find themselves isolated in Naraka, a place of torment. Seowoon, was once highly ranked in his species, was known for his excellent combat capabilities, but he lost all of those abilities after being secluded in the Naraka. Instead, he gained the ability to detect the emergence of mutants through a “messenger”. To escape Naraka, they need a Wu Ore, a by-product of the mutants, but Seowoon can’t even get close to mutants without being killed. Upon learning the truth, Cahaya makes a proposal to Seowoon. “From now on, let’s work together, be my mutant notifier”. With Cahaya’s help, he is able to travel back and forth to Seoul, but Seowoon finds it more and more difficult. “Why did I push you away…….” He just wants to deny the feelings that draw him towards Cahaya.