The Japanese cast includes Hikaru Midorikawa as GridmanYūya Hirose as Yūta Hibiki, Hikaru Midorikawa as Gridman, Sōma Saitō as Shō Utsumi, Yume Miyamoto as Rokka Takarada, Reina Ueda as Akane Shinjō, Tetsu Inada as Alexis Kerib, Ryousuke Takahashi as Samurai Caribar, Katsuyuki Konishi as Max, Aoi Yūki as Borar, Masaya Matsukaze as Vitt, Kenichi Suzumura as Mysterious Boy, Mayumi Shintani as Rikka Mama, Akari Kitō as Hassu, and Suzuko Mimori as Namiko.
Yūta’s friends — Shō Utsumi, Rikka Takarada, and Akane Shinjō — would always help him and spend their days with him.
Yūta Hibiki, who is a first-year high school student living in Tsutsujidai, one day wakes up to find he has lost his memories.
The English cast includes Brandon McInnis as Yuta, Robert McCollum as Gridman, Jill Harris as Rikka, Greg Ayres as Utsumi, Lindsay Seidel as Akane, and Barry Yandell as Alexis.