- Kirihiko: "Fuuto really has a nice wind blowing through it."
- "N" stands for Nazca and Nemesis
- Part one's title is "Memory Kids".
- Part two's title is "Friends in the Wind".
Our story opens with Double duking it out with the Nasca Dopant in a park someplace in Fuuto...
...no, wait, getting ahead of ourselves. Our story opens in the barbershop Barber Kaze, where Shotaro goes for his regular shave and hot-towel-on-the-face treatment-thingy, where he strikes up conversation with another regular customer, supposedly the man who designed the Fuuto-Kun mascot out of his love for this city, even though they never see each others' faces thanks to said hot towels. And then the towels come off.
Turns out it's Kirihiko Sonozaki himself.
Then the action moves to the park, where Kirihiko as Nasca demands to battle Double as FangJoker—but the Fang Memory's gone MIA since the last time, so Shotaro goes into regular Double and the story catches up with the opening. The battle gets called off when the barbershop owner walks right in on the scene. Turns out he needs Shotaro's help to track down his daughter Akane, rising track star and another old friend of Shotaro from yey long ago.
On the Sonozaki family side, Kirihiko has somehow remained oblivious to the Dopant Memories' negative side—not just the physical effects, but the inner dealings of Museum. And it's not just him, as Wakana giving up her Claydoll Memory comes back to bite her this week as her father Ryuubei puts it back in her hands. Worse than that, the fact that Phillip has been revealed to be their missing son Raito is kept secret between Ryuubei and Saeko, along with the truth behind Kirihiko's evolving Nasca Power Levels.
Shotaro returns to the Agency and finds it an utter mess—not from Phillip going overboard in his research, but rather going overboard in trying to catch the Fang Memory, with every known type of vermin trap strewn all over the place. After Shotaro explains the barber's case, he and Akiko set off to investigate and leave Phillip to find Fang Memory on his own...riiiight after Wakana's radio show is done.
Thanks to Queen and Elizabeth, our heroes learn that Akane may have fallen in with the wrong crowd. And all the signs are there—she's not just older, but her attitude has worsened, she refuses to go home, and her new friends Touma and Yuuichi aren't going to take it lying down. And they're prepared to deal with meddling adults like Shotaro, of course...with a Dopant Memory of their very own. Yuuichi snags it and turns into the Bird Dopant, conveniently confirming those rumors of a bird-creature flying around Fuuto that were mentioned in Wakana's radio show...which you might have heard if you stayed behind with Phillip earlier.
It's Rider Time...which hits a snag as Phillip claims to have caught a (mechanical) kabutomushi or Hercules beetle in one of his traps. Despite this, Shotaro manages to go Double just in time, and has no problem wiping the floor with Bird Dopant considering it's just a kid...but things get tangled as it turns out Touma can use the Bird Memory as well. He makes his escape, Akane is dragged off with him, leaving Yuuichi wracked in pain as the whole area he plugged the Dopant Memory into starts smoldering. And Kirihiko, secretly watching the whole thing, realizes that these are just kids with a Dopant Memory in their hands, and smells a vermin of his own—a rat.
He confronts Saeko on the matter, but she claims it's all taken care of, even as Yuuichi winds up in intensive care. Shotaro digs up more of the story—the kids treated Bird Dopant as a thrill ride at first, until Touma decided it could be used for violent purposes. He starts a string of seemingly random attacks, and Shotaro figures out the next target...
...a ramen stall, where Jinno and Makura happening to be talking about this new ace cop transferring over soon. As if confirming their suspicions, Akane gets there ahead of our heroes to warn them, right before the current Bird Dopant and Shotaro barge in.
It's Rider Time again... except this time Phillip shows up in person (with the RevolGarry and Akiko for backup), armed with a hypothesis on the Fang Memory's behavior: it shows itself when Philip himself is in danger. The Bird Dopant lashes out at him, and sure enough, the Fang Memory shows up and takes the hits for Philip. Phillip and Shotaro go straight into Double as FangJoker, gaining an added edge as they take down the Bird Memory...
...except that the Bird Memory had no response to the Memory Break. Indeed, Touma's arm starts smoldering as well, and Kirihiko conveniently shows up to take it back and voice his concerns. Then he becomes Nasca Dopant and attacks FangJoker right there and then, to settle the score. This time however, Fang gives Double an added edge, even before Nasca's evolving abilities somehow give out on him—but Shotaro calls an end to the fight, just before Phillip can put the Arm Fang wrist deep into Nasca's neck. Turns out a convenient Fuuto-Kun poster reminded Shotaro of the real priority here, and he gives Kirihiko a chance to man up and do the right thing for once.
Back at the agency, Phillip find the thread between all of theBird Dopant's victims—Touma's been targeting the parents of any students rivaling Akane at the track events. And the unusual Dopant Memory behavior—the smoldering that Yuuichi and Touma both suffered—came about because Akane herself is the only legitimate recipient, but gave in to peer pressure and let the boys use it for themselves. At the same time, Kirihiko is doing some digging of his own, and learns that Museum has been bending its own rules and letting kids use Dopant Memories solely for research purposes. Unfortunately, both parties soon find themselves in over their heads—Akane's Dopant Memory withdrawal leads her to bash past Phillip and Akiko on her way out the agency (and right into Saeko's hands!), while Kirihiko makes the mistake of threatening Sonozaki Ryuubei (a.k.a., the TERROR DOPANT) while his own Dopant Memory was giving him problems.
While Kirihiko does get some vital information before having to flee for his life (with Mick as Smilodon on his tail), Shotaro has some help from Phillip in tracking down Akane—albeit too late, as Saeko has already returned the Bird Memory to her, after Dopant Memory withdrawal has sent her right over the edge. It's Rider Time yet again, and this time our heroes need a little backup—Shotaro summons the RevolGarry to enable HardTurbuler and chase the Bird Dopant down. Meanwhile, Kirihiko nearly gets turned into kitty litter, except for an intervention from Wakana as Claydoll of all people. Kirihiko thanks Wakana for the help, departing with "I always liked your radio show."
Having the advantage of flight doesn't help Double a lot as the Bird Memory has done some evolving of its own—until Kirihiko as Nasca appears, grounding Akane and showing Double how to target the Gaia Memory physically and end the problem at the source. It works: Double as CycloneTrigger uses the Bat Shot as a Trigger Magnum attachment for added accuracy, finally breaking the Bird Memory. While Akane will be fine, Kirihiko's own Dopant Memory problem has only gotten worse. His final act is to pass his own Fuuto-kun keychain to Shotaro, then find Saeko and beg her to flee the Museum with him...only she's in on it as well, and responds to his offer with a deadly plasma attack.
At least Kirihiko had a good spot to experience the winds of Fuuto...before becoming one with them. All that's left is his trademark red-spotted cravat, blowing in the wind...
Meanwhile, the robotic kabutomushi shows itself again at Narumi Detective Agency, before zipping off and folding up, as a man in front of the Fuuto Police Department catches it. A man who, in stark contrast to Kirihiko, hates the city of Fuuto. A man with a Gaia Memory of his own. A red one, labeled A for...
- Big Damn Heroes: The Fang Memory apparently has this for a command line, in regards to Philip, who's necessary for Kamen Rider Double FangJoker.
- Bittersweet Ending: The kids survive and Akane is free from the influence of Dopant, but Kirihiko gets killed by Saeko for trying to rebel against the Museum.
- A Death in the Limelight: Kirihiko's motivations and personal morals get a lot of examination here before he's finished off by his own wife.
- Enemy Mine
- Even Evil Has Standards: Zig-Zagged. Kirihiko is the one man in Museum against the selling of Dopant Memories to kids ("filthy adults" being fine with him), but this establishes him as the Anti-Hero.
- In Medias Res: The story opens with Nazca and Double already in combat. It then jumps to how the battle had started—30 minutes prior, at the barber shop.
- Japanese Beetle Brothers: The appearance of Terui Ryu/Kamen Rider Accel's Beetle Phone, a remold of the Stag Phone, ticks off the checklist for this season.
- Missed Him by That Much: Seconds-based variation. Kirihiko and Shotaro both sit up during their hot-towel treatment thingy, causing their face towels to fall off, but the Barber Kaze staff set them both back down before either can get a good look at the other. It's only when the timer goes ding! and the staff take the towels off themselves that...well, see "You!" Squared below.
- Not So Different: Kirihiko and Wakana, despite being at loggerheads all this while.
- Power Levels: While Kamen Rider Fourze had formal names for this phenomena in Astro Switches, the Gaia Memories have been graded with unofficial ones depending on their length of usage, and that's before we even learn about T2 Memories in The Movie.
- She Is All Grown Up: Inverted. Shotaro has apparently known Akane since childhood, but remained fatally oblivious to this.
- Shout-Out: The kids believe the Dopant Memory can turn them into superhumans, read as 'choujin', but they actually become the Bird Dopant, a "bird-man" (also read as choujin). This was the intended meaning for the title for Choujin Sentai Jetman.
- Would Hurt a Child: Museum will let children get ahold on Gaia Memories, which can have consequences. Kirihiko is not okay with this.
- Xanatos Gambit: Museum. One way or another, they get valuable data about Dopant Memory behavior. And they really don't care if you're a child...or an in-law.
- You Have Outlived Your Usefulness: Turns out Kirihiko is merely another test subject for Museum, one for the Nazca Memory. And now that his body's condition is deteriorating from his merely being at level 2, Museum has no further use for him anymore.
- "You!" Squared:Shotaro and Kirihiko: [both laughing, before looking at each other]
Kirihiko: [as both sit up, to the barber's confusion] You cur!
Kirihiko: Out front!