Niches, a malevolent demon residing in Hell, perpetually wears sunglasses that conceal his eyes entirely, even within Hell's darkness. He collaborates closely with another demon, Hisler. Their dynamic casts Niches as the manipulative and deceitful Blue Oni, contrasting Hisler's overtly violent Red Oni persona.

His core mission involves subverting human faith in spiritual concepts like God or Buddha. Niches frequently deploys his signature declaration, "God is dead," both as a victory cry and an ideological weapon. He actively corrupts others by inviting them to join him in forging a "new world" rooted in atheism, asserting that many on Earth have already awakened to the "truth" of non-existent higher powers.

During the climax, Niches confronts the protagonist Ryuta directly, offering him a place among demons to rule together. When Ryuta rejects this and challenges Niches—questioning why such a "superior intellect" would remain confined to Hell if his worldview were correct—Niches reacts with furious rage and collapses. Following this defeat, Hisler summons a demonic elephantine creature to assault Ryuta. Niches meets his final end when he, Hisler, and their summoned creature are obliterated by luminous energy emitted from a mecha piloted by Ryuta and Yuko. His last act is screaming "I AM DEAD" before annihilation.