This article is about a/an episode in Kamen Rider Build.

That One with the Best Match (ベストマッチな奴ら Besuto Macchi na Yatsu ra) is the first episode of Kamen Rider Build. It features Build's on-screen transformation (in the show) as RabbitTank. It also features the debut of Build's HarinezumiTank form.


A mysterious object known as the Pandora Box was brought back from Mars. In effect, Japan was divided into three by giant walls produced from the box. 10 years have passed since that day. This story takes place in one of the city capitals, Touto. Mysterious organisms known as Smash are terrorizing humanity. A physicist saves people from the Smash and pursues the mystery hidden within the Pandora Box. His name is Sento Kiryu. People call him... the Kamen Rider.


Ten years ago, Japan became the first country to successfully send a manned probe to Mars. In what appeared to be the ruins of an extinct Martian civilization, an astronaut discovered a mysterious cube, which would come to be known as the Pandora Box. At the return ceremony for the expedition, a security guard suddenly rushed forward for the Pandora Box. As he touched the artifact, a flash of light erupted, and a massive wall rose from the ground, splitting Japan into three regions: Hokuto in the north, Seito in the west, and Touto in the east. The rising of the wall, now known as the Sky Wall Disaster, prompted regional tensions, dividing Japan even further.

In the present day, Touto's government is in possession of the Pandora Box, and has formed the Touto Institute of Advanced Matter Physics, headed by Gentoku Himuro, in order to decipher the artifact before foreign countries attempt to seize any of the three regions. There have been numerous reports of Touto citizens being attacked by strange creatures known only as "Smash", as well as a mysterious hero nicknamed "Kamen Rider" saving people from the Smash. While being interviewed by journalist Sawa Takigawa, Himuro is informed about Sento Kiryu, a researcher applicant with promising test results. Later that night, Takigawa is attacked by a Smash, but is saved by the Kamen Rider. The Rider extracts something from the Smash using an Empty Fullbottle upon defeating it, causing it to revert to a human form.

The next day, Sento awakens from his sleep as he remembers some of his past memories, including being experimented on by scientists using gas masks, lead by a bat man. Upon his awake however, he saw his face had been drawn on with marker. Sento already knew who did it, but temporarily diverted his attention as the Fullbottle he extracted last night had been purified by Misora into the Hedgehog (Harinezumi) Fullbottle. As Sento excitedly examines it, Misora emerges from the Fullbottle purifier and flops onto a bed to sleep, too tired to even respond to Sento. In an act of revenge, Sento then smears her face with marker (drawing many physics formulas) before leaving his underground base.

Upon reaching the surface of his underground base, namely cafe Nascita. Sento is greeted by the cafe owner, Soichi Isurugi, who startles him in return. After showing Soichi the Harinezumi Fullbottle, Soichi promptly asks Sento if he got any clues about his past life. Sento replied that aside from the scientists in gas masks, humans experimentation and the mysterious bat guy, he was still lacking. Soichi then reminds him that he has a year worth of rent for the underground base. Sento, now realizing that the rent bills are the reason why Soichi asked him to apply for the job at the Touto Institute of Advanced Matter Physics and that he's about to get late on his first day, shows Soichi another of his inventions: the Build Phone and Lion FullBottle. Soichi teases him as if he were to call in sick, but Sento instead combines the two items to transform the Build Phone into the Machine Builder. After Sento sets off, the view changes to a sewer where a shirtess fugitive is making an escape. After arriving aboveground and changing clothes, Touto Guardians manage to track and find his location.

At the Touto Institute, Gentoku gives Sento an orientation about what he is about to research, mainly the Pandora Box. Upon asking about Sento's applicant resume, Gentoku is visibly surprised to read that Sento is amnesiac. He later ask Sento if he knows about the Sky Wall Incident, which Sento complies. Gentoku added that the effect of the Sky Walls weren't just region separation, but everyone there had turned aggressive over the artifact.

Suddenly, Gentoku receives a report that the fugitive Banjo Ryuga had defeated the Guardians who surrounded him, bare handed, and was now making his escape once more using a stolen Guardian bike. Sento was also informed about this discreetly by a text from Soichi. Sento then learns that Ryuga was once a pro fighter, but got banned for life for fight fixing. Ryuga was also accused and arrested for murdering one of the Touto Institute's researchers, Takumi Katsuragi. Sento later decides to chase him personally with Soichi guiding.

Sento successfully intercepts Ryuga by exploding the path in front of him. Ryuga asked who Sento is, to which he replies that he's going to catch him for his crimes. Ryuga, however, adamantly exclaims that he never killed anybody. Sento doesn't believe him, but then Ryuga mentioned something about being used as a guinea pig. As Sento takes interest in this statement, Ryuga suddenly attacks him; Sento then uses the Rabbit FullBottle ability to take the upper hand and strikes back successfully.

Taken aback, Ryuga then explains that there were gas mask scientists who experiment upon him. He remembers a bald security guard injecting him with something that knocked him out; whe he awoke, there were people with gas masks starting to dose him with some kind of gas. Halfway through, Ryuga managed to escape, beat up some of the scientists, and run away. Sento then asks if Ryuga had seen a bat man to which Ryuga angrily exclaims that he knows nothing about him. However, their argument is cut short when a Smash appears and starts attacking them. Ryuga tries to fight the Smash barehanded, but it's far too strong for Ryuga to handle. Sento then admires his spirit and transforms into Build Rabbit Tank Form.

The battle between Build and the Smash continues as Sento switches to Harinezumi Tank Form to counter  the Smash strength, reverting back to Rabbit Tank form to activate his Vortex Finish. After he extracts the Smash essence into a empty FullBottle, Ryuga realizes that the Smash was another person that he saw when he was being experimented on. However, upon further interrogation, the man is shown to have short-term memory loss. In despair, Ryuga begs Build to believe in him; Build concludes that the experiments are to turn people into Smash. Unfortunately, Gentoku, Utsumi and some Touto military forces arrive and ask Build to hand Ryuga over to them.

Ultimately, Build decides to trust Ryuga and helps him escape, thus making him a fugitive as well. After their successful escape, the bat man appears and announces the beginning of a war.


Guest Casts

Suit Actors


  • Bottle used:
    • Build
      • Biotic: Rabbit, Lion (in Build Phone), Harinezumi
      • Abiotic: Tank
    • Night Rogue
      • Bat
  • Form used:
    • Build
      • RabbitTank Form, HarinezumiTank Form


  • While Sento is explaining his the mechanics to his Build powers to Misora, there is one shot of him all cleaned up, similar to the state he was while he was leaving his lab. This could be due to a mis-arrangement of footage shot before and after the lab explanation scene.
  • When Sento cranks the lever to transform in front of Ryuga, he cranks the lever slowly, but in the next close-up shot of his driver, he's unexplainably cranking it twice as fast as before.


Build EP1 CS
  • Closing Screen Fullbottles:
    • Kamen Rider: Build
    • Fullbottles:
      • Biotic: Rabbit
      • Abiotic: Tank
  • Count at episode end
    • Bottles in Build's possession:
      • Biotic: Rabbit, Harinezumi, Lion, Kaizoku
      • Abiotic: Tank, Diamond, Gatling, Soujiki, Light
    • Bottles in Night Rogue's possession: Bat
  • Just like Ex-Aid's first episode, this episode takes its name from part of the main Rider's transformation announcement (i.e. Best Match).
  • The Sky Wall incident 10 years ago initially does not seem to fit with the rest of Kamen Rider continuity, since the incident was said to have divided Japan into three separate districts; however, Japan was shown to be intact throughout the past 10 seasons of the Kamen Rider Series.
  • References to the original Kamen Rider:
  • The color of the spacesuit on Mars was adjusted with a filter in this episode.

DVD/Blu-ray releases

External links


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