|This article is about a/an movie-exclusive villain in Kamen Rider Fourze.|
|Villain Type:||Space Ironman|
|Season:||Kamen Rider Fourze|
|Homeworld:||Earth (Main Timeline Continuity)|
|First Appearance:||Kamen Rider Fourze the Movie: Everyone, Space is Here!|
|Last Appearance:||Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z|
|Number of Episode|
Groundain (グランダイン, Gurandain) is the blue car-like older brother of the Kyodain.
Groundain was created along with the other Space Ironmen by Professor Blink. However he and sister Skydain went rogue and attacked the professor. The professor siphoned their power and kept them sealed within the Space Core. In order to get their powers back and start their plan, Groundain posed as the general manager, Harumi Saeba of OSTO Legacy and recruited the Kamen Rider Club to deal with Black Knight and Inga Blink and power down XVII. With the Space Core powered down, the Kyodain regained their forms and attacked the Club before going on with their plan to use XVII to destroy humanity.
Kamen Rider Fourze in Cosmic States managed to stop their plan by warping the orbital laser back at XVII, ceasing its functions. The Kyodain then attack the powered down Fourze and Meteor. When it seemed hopeless, Fourze gained the power of the Fusion Switch and Fusion States. The Kyodain assumed their vehicle forms as Fourze rode on his Machine Massigler, before Fourze made the finishing blow with Fusion States' Limit Break, destroying the Kyodain.
He is armed with a powerful cannon built into his chest called the Grounbuster X (グランバスターX Guranbasutā Ekkusu?). Groundain also has the ability to use his Cosmic Energy to summon Dustards like the Horoscopes. Groundain is able to transform into a car-like form known as the Grouncar.
- Groundain is an homage to Grounzel from Space Ironmen Kyodain.