Korudo is a 12 year old girl who has grown up in a world of mistrust. She covers her problems with jokes and teasing, and she can't take anything seriously. Korudo decides to take the Hunter Exam in order to achieve her goal of finding her parents. She certainly never thought she'd meet two very unique boys along the way. She finds a specific white haired boy intriguing, and easy to mess with. He finds her annoying due to her constant teasing, which in return causes many arguments. As she goes on adventures with the duo, she finds herself falling for the assassin, much to her displeasure.

Tudo se resume ao dia, quando os heróis percebem que não podem vencer. S/N é um jovem de 14 anos que fará de tudo para alcançar seu plano, sua promessa que ele fez. Ele nunca sonhou em se tornar um herói, porque foram eles que o injustiçaram. E não havia nenhuma maneira no inferno, que ele não iria se vingar por isso.