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

Rider Wars Start (ライダーウォーズ開戦 Raidā Wōzu Kaisen) is the seventeenth episode of Kamen Rider Build. It features the debut of Kamen Rider Cross-Z Charge, the full appearance of the Wolf and Smapho Fullbottles after their video appearance in episode 9, the Kuma, Televi and Hellicopter Fullbottles and the full debuts of Kazumi Sawatari, Akaba, Aoba and Kiba. It also features the in-series debut of the Phoenix and Robot Fullbottles after their appearance in Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders.


At last the war has begun! Instigated by virtue of Hokuto through their prime minister's actions, the Touto government officially instigates the Kamen Rider as their military weapon. "I do not intend to become a tool of war" Sento replies. There is a reluctance in Sento's words though, as he realizes that the outbreak of this war was also due to him creating the Rider System and the Smash. Just what decision will these two warriors make?


to be added


Guest Casts

Suit Actors


  • Bottle used:
    • Build
      • Organic: Rabbit
      • Inorganic: Tank
      • Other: RabbitTank Sparkling
    • Cross-Z (Charge)
    • Grease
      • Organic: N/A
      • Inorganic: Helicopter
    • Blood Stalk
      • Organic: Cobra
      • Inorganic: N/A
    • Castle Hard Smash
      • Castle
    • Stag Hard Smash
      • Kuwagata
    • Owl Hard Smash
      • Fukurou
  • Form used:
    • Build
      • RabbitTank Form, RabbitTank Sparkling Form


  • Jelly used:
    • Cross-Z Charge
      • Dragon


  • When Kazumi destroyed a Smash with his powered punch, after the Smash turns into green flame, no human body is seen on the ground, even though Smashes should have turned back into their original human form after they are defeated.
    • It is possible that the human casualty was simply obscured from view, since the camera never focused on the exact spot where the Smash landed on again after it was defeated.
  • When Banjou transforms into Cross-Z Charge for the first time, the standby tune from the Sclash Driver is inaccurate, as it only loops the beginning part of said tune.


Cross-Z New CS
  • Closing Screen Fullbottles & Sclashjellies:
    • Kamen Rider: Cross-Z (Charge)
    • Fullbottles:
      • Organic: Dragon
      • Inorganic: N/A
    • Sclashjellies:
      • Dragon
  • Count at episode end
    • Bottles in Build's possession:
      • Organic: Rabbit, Gorilla, Taka, Ninjya, Panda, Harinezumi, Lion, Kaizoku, Octopus, Phoenix, Wolf, Kuma
      • Inorganic: Tank, Diamond, Gatling, Comic, Rocket, Syoubousya, Soujiki, Densya, Light, Robot, Smapho, Televi
      • Other: RabbitTank Sparkling
    • Bottles in Cross-Z (Charge)'s possession:
    • Bottles in Grease's possession: Helicopter
    • Bottles in Night Rogue's possession: Bat
    • Bottles in Blood Stalk's possession: Cobra
    • Bottles in Castle Hard Smash's possession: Castle
    • Bottles in Stag Hard Smash's possession: Kuwagata
    • Bottles in Owl Hard Smash's possession: Fukurou
    • Jellies in Cross-Z Charge's possession: Dragon
    • Jellies in Grease's possession: Robot
  • The episode's title mirrors Kamen Rider Decade's episode, Rider War: Prologue, and the Rider War concept as a whole.
  • This episode doesn't introduce a recap of the last episode as prior episodes have.
  • Incidentally, the premiere of Kazumi's debut was accompanied by a promo for the Blu-ray Box release of Kamen Rider Kiva, in which actor Kouhei Takeda previously starred as Otoya Kurenai.
  • This is third episode after episode 1 and 10 which none of actors are narrator.

External links