Hondomachi may not be a superhero who got her deductive powers from a hole drilled in her head, but that bizarre injury offered her unique perspective into someone like Kazuta Haruka, whom she meets in the street and who kisses her before fleeing.
For her, everything suddenly points to Haruka, a former victim of the Perforator, being the Gravedigger. Their equipment hasn’t been able to detect his killing intent because when he has a sudden urge to kill he reacts with a gesture of love instead—a kiss—and would therefore kill those whom he loves.
Sure enough, cognition particles are found an an Id Well is opened, into which Sakaido is injected. He enters the well in the middle of the sky falling at great speed, but manages to land on a floating island containing a house later identified as belonging to Kazuta.
Once Sakaido’s memory is activated by the sight of a murdere Kaeru, he looks under her carefully-spread pool of blood to find a girl hiding who has shifting features and voices—a composite of the Gravedigger’s victims.
Sakaido also finds shards of a photo also found when Kazuta was a victim, and Hondomachi and Matsuoka are dispatched to meet with those in the picture one by one while Nishimura and a SWAT team head to the site of Kazuta’s house, now a soy sauce brewery.
The composite girl said her boyfriend went out of the house to fight the “monster”, and when Sakaido heads out he quickly learns that monster is John Walker, who kills the “boyfriend”, dodges Sakaido’s attacks, and flies off with that trademark tip of his hat.
As Hondomachi diligently interviews the “cutest” of the people in the photo, Inami Nahoshi, Nishimura and his team discover vats that could contain victims, but are blown up in the brewery—it was all a trap. Meanwhile Hondomachi is unafraid to pry as far as she can with questions relating to Inami’s love life. Inami also seems all too happy to clean her head wound when it suddenly starts bleeding.
By the time Matsuoka gets word of the trap, Hondomachi has Inami cornered, revealing her to be a sadist using Kazuta’s scrambled romantic and murderous urges to her advantage by having him commit the murders for her. Hondomachi moves to arrest Inami and demands to know where Kazuta is; meanwhile, he’s lurking nearby with a knife.
It’s interesting to see how both Hondomachi and Sakaido have been elevated in their deductive ability by their respective marks (the former, her head wound; the latter, his crime) In the Id Well, Sakaido is the Brilliant Detective, as well as a Mission Impossible-style action hero. But in the real world, the ace detective is without doubt the recently wounded but no-less-relentless Hondomachi.