Voice Range: Mid-Low to Mid-Level Pitch

Seth is an assassin out in the night with particular interest in the Princess of the Night Blade. Seth's ancestral lineage dates back to the schism that occurred within the Night Blade organization and he is the descendant of the moderate faction that sought to keep their teachings hidden and obscure their abilities as much as possible. This group operates to this day in upholding the ancient ways of the Night Blade and Seth's position as one of the head family's successors has him reluctantly carry out his family's wishes to watch over the night. It is revealed that he met Linne 10 years prior to the story and pitied her tortured existence over the centuries. He swore to her that he would save her from her curse but he was powerless to do anything in the decade that passed. A glimmer of hope to rekindle his promise appears to him and he heads out into the night to finally set things right to his promise and free Linne of her curse. Despite his status as Hyde's rival and his notable proficiency in his profession as an assassin, he is only a first-year in highschool.

He's an extremely serious individual and never shows any emotion beyond stoicism. Although his cold attitude may come off as insensitive, he is greatly burdened by the mistakes of his ancestor and feels that if he fulfills Linne's wish for death, he can redeem his family name and free himself of the past. In Yuzuriha's story, her optimistic way of life despite her family's history briefly causes Seth to question his path and his individuality.