Kyouya Onodera

Kyouya arrives at the remote island academy alongside the protagonist, concealing an extraordinary ability — true immortality. Despite his cold demeanor and reluctance to form social bonds, he possesses a razor-sharp intellect that few can match. When classmates begin vanishing without explanation, Kyouya launches a solo investigation driven purely by suspicion and logic. His recurring mental duels with Nana form the narrative's most electrifying tension, cementing his role as the story's de facto detective and primary intellectual antagonist.