Nishiya, a university professor and an acquaintance of Genba Ryougoku, serves as a minor but pivotal supporting character in the narrative. He initially presents himself as a helpful academic, informing the protagonist Tatsumi Saiga about the retrovirus that has been activated within Saiga's body and introducing him to the researcher Seiji Ochiai. However, Nishiya's motivations are rooted in a selfish desire for personal fame and recognition. He betrays Saiga by selling him out to the Roppongi Club so he can conduct his own research on Kagura Tennozu. Feeling double-crossed himself later, Nishiya kidnaps Kagura and deliberately ingests a bottle containing the virus extracted from Saiga, intentionally making himself a carrier. In a desperate attempt to gain euphoric powers for himself, he attempts to assault Kagura but is stopped by Prime Minister Kamiya's men. His actions lead to his demise when he is devoured by a mutated Kamiya, with his dissolving corpse seen in the politician's mouth.