The film opens with a mysterious figure Dr. M2 rallying a cadre of Death Mechanics—massive, blue, Vulcan-inspired robots built from a boy’s toy scraps and clever engineering. He singles out one unit, Death 18, and issues a chilling directive to seize Kiyomaro Takamine, setting in motion a collision between two very different visions of friendship and power.
Meanwhile, Kiyomaro Takamine is rushing to catch the Coast School bus after oversleeping, with his loyal companion Gash in tow. Gash has a long memory of the various generations of Vulcan—each a friend and a reminder that connection matters. As Kiyomaro races, [Gash] notices that his current Vulcan ally, Vulcan, is only partly intact, stuck in a tree, and asks his friend to fix it. Kiyomaro vows to “make him a new one,” even as the bus pulls away and the chase returns to the quiet streets below. In a sudden swoop, Death 18 descends and abducts Kiyomaro, leaving Gash stunned and the town buzzing with questions.
Inside Dr. M2’s lab, the demon hosts a stark, otherworldly demonstration. He explains that Kiyomaro could become his partner and the key to traversing to a future demon world. To prove his point, he reveals Death Mechanics that resemble his own Vulcan creations. He also shows a prototype Vulcan—a buggy glimpse of a future version that Kiyomaro might one day build, highlighting both the promise and the peril of such power. Yet Kiyomaro resists the offer to leave with him, insisting that he has to stay with his friends and that Gash’s view of people has already shifted his own.
Back in Mochinoki Town, Gash, along with his demon friends Tio, Kanchome, and Umagon, returns to town and reclaims a sense of normalcy. They discover graffiti beneath a bridge, where Gash scrawls the name of his new ally, Parco Folgore, in Kanji on the metal frame of the robot he’s come to trust. The group settles into a playful mood, and the bond between demon friends and human companion begins to feel more tangible than ever.
As Dr. M2 opens a portal to the future, a looming storm casts its shadow over the city. Citizens are urged to evacuate while Gash’s newfound ally, Yondaime, struggles against his programmed hesitation to protect everyone. Eventually, Yondaime accepts the role and soars toward the ominous cloud with the others, including Kiyomaro, who emerges from the lab’s containment.
The trio—Gash, Kiyomaro, and their demon friends—enter the floating castle of Dr. M2, where a fierce clash unfolds. Death Mechanics rally to attack, but Kiyomaro hijacks the moment, guiding Gash to unleash a powerful Zakeru spell that disrupts the mechanical assault. The onslaught tears a hole through the castle, sending Kiyomaro plunging toward the ground, only to be caught by Yondaime’s quick catch.
As the battle intensifies, Gash pleads for peace, insisting that the Vulcans—every last one of them—are his friends. Yet the Vulcans strike back in force, with Yondaime’s programming wavering under the pressure. The four demon-human pairs—Gash and his friends with Kiyomaro—fight to hold back the Vulcans, but the onslaught proves relentless. Megumi Ooumi, Parco Folgore, and Kafka Sunbeam arrive in a vehicle to join the struggle, and Megumi delivers a devastating counterattack using Giga Ra Seushiru, bending the giant Vulcan’s momentum back upon itself.
Amid the chaos, Kiyomaro and Gash realize their most important truth: Vulcan is not just a weapon, but a friend. Gash’s words cut through the noise, reminding Kiyomaro of the power of companionship—the real power he has shared and built with Gash since the beginning. In a tears-filled confession, Kiyomaro admits that the only gift he can give back to Gash is not a perfect robot, but his enduring friendship. The group resolves to protect the Vulcans as friends, not as instruments of conflict, and a plan forms to halt the threat without erasing the Vulcans themselves.
The plan hinges on severing the dangerous power source at the front of the enormous Vulcan by drawing power from everyone present. Dr. M2, hovering in the castle’s core, is coaxed into a final, desperate attempt to fix the reactor. The four demon allies cast a sequence of spells to channel their combined energy into the reactor, while Kiyomaro summons Gash’s signature spell, Baou Zakeruga, to guide the surge. For a tense moment, it seems as if the hole could reopen and doom Earth, but a hidden strength emerges: Yondaime’s reactor-attached form accepts the transfer, and the prototype Vulcan’s latent voice—carrying Kiyomaro’s own memories—speaks as a tether between them all. The transmission confirms that they will always be friends, regardless of time or distance.
With renewed resolve, the team releases a three-headed Baou Zakeruga that slices through the reactor and powers the final surge. The reactor roars to life, the storm subsides, and the time-space breach begins to seal itself. The three Baou Zakerugas race into the cloud, and the enormous Vulcan collapses. The smaller Vulcans break free and scatter into the sky, their safety secured by the united effort of the group. In the aftermath, Gash asks if he might ever see Yondaime again, but Kiyomaro reassures him: a better Vulcan—an even better friend—will be built. The two friends share a moment of quiet triumph, aware that their bond has reshaped what friendship means in this world and any future one they may face together.
