"Active Interest" is the sixth episode of the Durarara!! anime.
8 hours previously, Asanuma, Morita, and Kanazawa arrive at a dilapidated hotel to look for illegal immigrants to sell. They debate taking teenage girls but don't want the Headless Rider to show up again. Instead, they take a middle-aged man to their car and try to drug him, but Kanazawa is bumped by the struggling immigrant and accidentally spills the bottle of chloroform all over himself.
Kyouhei receives a text from Kaztano saying he broke a plate, and Erika thinks he may have messed up his kanji and meant to say he'd been kidnapped.
Mikado, Masaomi, and Anri are eating at Russia Sushi and discussing Mika Harima's disappearance. Mikado tries to assure Anri that he doesn't think Mika was kidnapped and killed by a gang, but this only worries Anri more.
The kidnappers' van almost runs over Shizuo and Tom because the kidnappers, affected by the fumes of the spilled sedative, are having trouble staying awake. Kaztano, seeing his phone in the sleeping Kanazawa's pocket, suggests they throw him out, as the drug that is making the others sleepy is on his clothes. The other two kidnappers comply. Kyouhei's gang arrives at Kaztano's place and discovers that he was kidnapped. Saburo is deeply affected, and Kyouhei decides they will find Kaztano for his sake. Hashim, a young boy who witnessed the kidnapping, describes the kidnappers' van and gives them the license plate number. Kyouhei calls Shinra Kishitani to ask Celty to rescue the foreigner. Shinra passes the license plate number along to Celty, informing her that the kidnappers are just henchmen for some bigger organization.
Elsewhere, a woman informs a subordinate that she wants more subjects. When he objects, she threatens to make him a subject. She picks up a photo of herself and Seiji Yagiri and thinks about a woman's head in a jar.
Erika suggests they try calling Kaztano's cell. Izaya Orihara picks up, saying he just happened to be walking by when the phone in the pocket of a man sleeping on the side of the street rang. He informs them of his location and is forced to run when Shizuo sees him and gives chase.
Kyouhei's crew discovers Kanazawa where Izaya had found him and tries to wake him up, Kyouhei refusing Erika and Walker's offer to torture him, to no avail. Kyouhei calls Morita and Asanuma on Kanazawa's cell, impersonating him, and asks the other two where their meeting place is. When Kanazawa wakes up, he sees Kadota's crew and asks who they are. They inform him that they are the Dollars before Saburo knocks him unconscious with a punch.
In a flashback, Kyouhei thinks about the day he joined the Dollars. He received an anonymous email with a url and a password, so he joined because the Dollars had no rules. No one has ever seen, met, or even knows the identity of the leader, and Kyouhei likes that he isn't taking orders from anyone. However, he is curious as to who the leader is and suspects Izaya.
At the designated meeting place, the kidnappers see a car coming and think it's their bosses, but they are surprised to see Kadota's crew pour out of the van. As they prepare to fight, they see Celty approaching. The kidnappers let Kaztano go, and as Kyouhei and the others pull him into their van, Saburo resumes the chase. Celty decides her job is done.
Saburo manages to corner the kidnappers' van, and the two spill out of the van and attempt to flee. Morita escapes, but Asanuma attempts to climb a fence and is dragged back by Kyouhei, wanting information on the kidnappers' boss. They hold him in their van, where Erika and Walker give him a stack of manga to allow him to choose what type of torture he would prefer. Kyouhei warns them not to use gasoline in the car again, which alarms the captive kidnapper. As Kyouhei waits outside, Kaztano and Saburo arrive in time for the 'morning ritual,' where everyone drinks milk. The kidnapper inside the van can be heard screaming and volunteers the information. He shows Kadota's crew the way to his employers at Yagiri Pharmaceuticals. Kyouhei finds this hard to believe, but he concedes that in Ikebukuro, there's usually a lot more to everything than one would think.
Seiji Yagiri calls the woman from earlier, and she tells him he can take all the money he wants. Seiji thanks her, calling her 'Sis,' and take the hand of the girl next to him, whose face resembles the head in the jar.
TarouTanaka says a classmate of his has gone missing. Kanra informs them of recent rumors he heard about illegal immigrants going missing, and once they are taken, they are never heard from again. Setton thinks Kanra likes rumors too much, but Kanra ignores this and says the Dollars are rumored to have taken and eaten the foreigners.
- To Anri telling Mikado and Masaomi about Mika having gone missing in episode 1.
- To when Celty stopped Asanuma, Morita, and Kanazawa from kidnapping Rio in episode 2.
- Most of the events in this episode occur before the start of the first light novel.
- During the car chase, Erika mentions an angel who flies through the sky shouting "Pi-piru-piru-piru." This is a reference to Bludgeoning Angel Dokuro-chan.
- A volume of Bludgeoning Angel Dokuro-chan is on the top of the stack of manga that Walker offers to Asanuma.
- The third manga in the stack is a volume of Ladies versus Butlers!
- While going to meet Kyouhei at work, Erika and Walker are discussing Cuticle Detective Inaba when they talk about a "little brother helper fairy character" and the "masochistic wolf with a hair fetish."
- While eating in Russia Sushi, Walker asks Saburo if he wants to "Itasha out your ride." Itasha (痛車, literally painful car) is a Japanese fashion term referring to decorating cars with images of (typically cute female) characters from manga, anime, and video games.
- As Seiji ends his call with his sister and walks away, he walks past a KFC sign and posters from Hell Girl and Baccano!, another work in the Naritaverse.
Walker: "This is the first time we've done something like this since we joined the Dollars, right, Kyouhei?"
Walker: "Saburo, wanna itasha out your ride? C'mon, it'll be so cool."
Saburo: "Wanna die?"
Kaztano: "Lookie! I Japanese! Why don't you understand?"
Morita" "Just give it a break."
Asanuma: "So you're saying your birth certificate says you're Japanese?"
Kaztano: "That is right you see? My birth certificate was burned up by firey air raids!"
Asanuma: "C'mon old man! You're not that old!"
Shizuo: "Iiiiizaaayaaa!!! Stay out of Ikebukuro!"
Kyouhei: "We're just glad we got our friend back safe and sound. It's as simple as that."