The name is a reference to the Nepenthes genus of carnivorous plants. They are pitcher-like plants that lure in insects with an alluring fragrance before trapping them in in their pitcher filled with flesh-dissolving enzymes to dissolve them. Whether Nephentesion No. 7 is made out of their acid is unknown.
In the anime, the chemical is a blue-colored liquid.
- Main article: Necromancer Arc
DA attempted to use the chemical on Hitokawa Hasami but were prevented from doing so by the return of Accelerator, who was waiting to catch them in the act. In the anime adaptation, Accelerator secretly took the Nephentesion No. 7 from the DA members as he left, before throwing the liquid towards them on returning.