Chapter 21

Mahito and Junpei keep dissecting their shared contempt for humanity. Above ground, Yuji, Nanami, and Ijichi build a strategy to trace the wave of disfigurement deaths across the city. Yuji is assigned to question Junpei, while Nanami heads underground to face Mahito directly.

In his hidden lair beneath Kawasaki City, Mahito shows Junpei grotesque experiments, giant and palm-sized humans he reshaped to test the limits of his power. He probes why the boy is at ease among corpses, and Junpei replies that he would only feel anger if a loved one were harmed, expecting cruelty from people and holding up indifference as the ideal. Mahito reframes that indifference as Junpei's private revenge on his species. He explains that souls exist separately from the heart and that he can see them, yet finds no value in any life. Encouraging Junpei to live exactly as he wishes, Mahito urges him not to confine himself to mere indifference.

Elsewhere, Yuji meets Nanami and Ijichi to review the disappearances and disfigurement deaths. Using residual data, they triangulate the culprit's hideout, but Nanami refuses to act on an estimate and instead directs Yuji to locate the other witness, Junpei Yoshino. With Yuji out of the room, Nanami confides to Ijichi that the killer is deliberately luring sorcerers into the lair, so he will go alone rather than endanger Yuji. Ijichi then drives Yuji to find Junpei in public, and they plan to use small Fly Head curses to gauge his sensitivity, with escalating instructions: rescue him if he cannot see them, bring him in if he flees, arrest him if he fights with jujutsu, and retreat if he proves a grade 2 threat or higher. Underground, Nanami cuts through ex-humans turned curses and demands Mahito show himself, voicing his distaste for killing humans and for overtime work. Mahito emerges, delighted Gojo did not appear, and declares Nanami the perfect subject for his experiments.

Part of the Vs. Mahito arc and collected in Volume 3, the chapter sets up the underground showdown between Nanami and Mahito while advancing Junpei's corruption. It was adapted across Episode 9 and Episode 10 of the anime. The action centers on Kawasaki City and Mahito's underground lair, with Satoru Gojo mentioned in passing.