At Futaba Kindergarten, three teachers gather to map out the plans for the upcoming annual sports day. Miss Matsuzaka [Makiko Ohmoto] suggests a samba routine, but Miss Yoshinaga [Yumi Takada] and Miss Ageo [Kotono Mitsuishi] dismiss the idea as impractical for the kids. The mood shifts late at night when a drunken Miss Yoshinaga is walking home and is suddenly confronted by a lurking, shadowy presence that mirrors her exactly, a chilling first hint that something uncanny is at play in Kasukabe.
The next morning, Shinchan arrives late yet louder than ever, delivering his trademark crude and crass off-color jokes and mooning toward Miss Yoshinaga. Surprisingly, she isn’t put off by Shinchan’s outrageous antics, which surprises Misae Nohara [Miki Narahashi]. The lesson planning continues, and to everyone’s astonishment, Miss Matsuzaka’s samba idea resurfaces as a viable option for the big day. Meanwhile, Masao Sato [Teiyu Ichiryusai] reveals a strange shift in Ai Suotome [Ayako Kawasumi]—she has begun addressing him with unusual affection, a change Masao suspects might be more than a simple crush. He can’t shake the feeling that Ai isn’t herself, or that a body double might be in play, a fear reinforced by Bo [Chie Sato] who brings up an urban legend about doppelgangers and people being replaced by look-alikes.
Back at home, Kazama [Toru Kazama, voiced by Mari Mashiba] notices something deeply disturbing: his mother’s dancing, the way she moves, and a strange ache in his chest as if something crucial is missing. When his mother’s face briefly twists into something ghastly, Kazama’s distress becomes undeniable, though he’s too young to articulate it properly. In Shinchan’s household, the samba fever leaks into everyday life as the family watches a samba festival broadcast from Santa Monica on television, intensifying the sense that appearances are dangerously deceptive.
The family heads to the shopping mall at the center of the mystery, where Hiroshi Nohara [Keiji Fujiwara] catches a fleeting glimpse of his own doppelganger. Misae spots her own clone wandering with a clones of Himawari Nohara [Satomi Korogi], while a clone Misae makes a brazen attempt to lure Shinchan away with chocolates. A mysterious, strikingly beautiful woman—whom Shinchan had befriended at the mall—rescues him and fights off the clone Misae. In a hidden section of the mall, masked figures in black capes destroy the clone with a blast that explodes like a firecracker, erasing the threat from sight. The family, who did not witness the skirmish, exits the mall visibly unsettled by what they glimpsed.
The next day, Misae urges Hiroshi to skip work, but he goes anyway, only to confront a second, more unsettling truth: his clone has replaced him at the office, reacting with uncanny calm to a dangerous accident—like a glass shard lodging in his brain. Hiroshi’s fear widens as he discovers that many people around him are doubles. At Kasukabe Station, the clone Kawaguchi and his band of cape-wearing conspirators close in on Hiroshi, who manages to escape and return home. There, he discovers that the Shinchan inhabitant of his house is also a clone, a revelation that triggers a tense showdown between the real Hiroshi and the doppelganger. The dog Shiro alerts them to the truth, and just as the clones tighten their noose, a car crashes through the house, delivering the mysterious driver—Jackie Feeney [Akeno Watanabe], the real Shinchan, and safety.
With the city under siege by doppelgangers, the kids retreat to the park for sanctuary until sunset, life-saving routines in place: if anything feels wrong, they will reconvene at the park. The clones descend upon the friends one by one. Kazama is overwhelmed by the clones of his mother and himself, while Nene Sakurada [Tamao Hayashi], Masao, and Bo escape the clutches of their maternal doubles and rush to the park, reassembling to regroup. The trio’s escape is short-lived, as the clone Kazama discovers their hideout and summons another wave of masked attackers, only to be blocked by the arrival of the Nohara family in a car, Jackie riding shotgun, providing a much-needed rescue.
Jackie reveals herself as a member of an international secret society called the SRI (Science Research Institute). Her mission is to investigate the mysterious clones, which first appeared during the Santa Monica samba festival. She explains that, aside from a handful of people who managed to survive the initial disruption, nearly every Kasukabe citizen has been replaced by a clone. These konjac-based “konjaclones” are manufactured by the deranged Brazilian-Japanese scientist Amigo Suzuki, whose goal is to replace ordinary people with pliant doppelgangers who will dance to his psychedelic samba at his command. Jackie seeks to escape the city, but the ubiquitous clones stand in her way. Bo’s knowledge cuts through the fog, and Jackie, Shiro, and the group race toward Amigo Suzuki’s hidden facility.
Inside, the konjaclone process unfolds before their eyes: Misae, Nene, and Bo are revealed to be manufactured out of konnyaku jelly, an everyday delicacy. Amigo Suzuki—a masked woman in black cape and lingerie with a no-nonsense samba obsession—confirms that she intends to choreograph eternity through forced dance, coercing the population to surrender to her rhythm. The Noharas and the children refuse to yield. Jackie leads an assault with her SRI team and Shiro’s keen nose guiding them to the production site, where they destroy the konjaclone factory’s infrastructure. The two women face off in a samba duel, and Jackie offers Shinchan a spark of courage in the form of a dance challenge, insisting that the fight can be won through joyous movement.
The confrontation escalates as Amigo’s konjaclone soldiers close in. Jackie hurls a formula that could liquefy the konjaclones, while the Nohara family and the children break the facility’s grip and free the imprisoned populace, who have been forced to dance against their will. The showdown isn’t easy: Jackie’s samba prowess initially falters against Amigo Suzuki’s wave of spectacular moves, but Shinchan’s audacious flair—specifically a moment where he cheers Jackie on and performs unabashedly—reframes the battle. He playfully prompts Jackie to dance in her own way, and his spirited, cheeky support becomes a source of resilience for everyone.
> dance as she likes
Seeing the crowd respond to a more authentic form of joy, Jackie redoubles her efforts, and the townspeople join in, dancing for their own happiness rather than for Amigo’s control. The konjaclones crack and melt away as the mass of people reclaim their autonomy. In a final twist, Amigo’s mask drops, revealing she is a clone of Jackie at first glance, but the konjaclone exterior dissolves to reveal Amigo is, in fact, a man who is Jackie’s father in disguise. Jackie thanks Shinchan for giving her the confidence to challenge his “samba” master and hands him a samba whistle as a token of victory and unity.
As the city’s sky finally erupts in a chorus of bright, festive fireworks, the konjaclones collapse into nothingness, and Kasukabe regathers in relief and relief-driven celebration. The story closes on a note of restored ordinary life, underscored by a renewed sense of community and the idea that people will dance best when they do so out of genuine joy, not coercion. The Nohara family, their friends, and their allies have survived a surreal, dangerous encounter with clones, and the city’s rhythm now belongs to those who choose to dance freely.
