The story revolves around Duke Fleed who is a survivor of the Vega Star, raised by Dr. Umon as his adoptive son, and known as Daisuke Umon on Earth. Years after his arrival, he's faced with the threat of King Vega and his army, who want to conquer the Earth. With his friends Koji and Hikaru (and later his kid sister Maria Grace), Duke decides to fight back using his best weapon, the almighty Grendizer.
Kei Tomiyama
Hiroya Ishimaru
Joji Yanami
Chiyoko Kawashima
Kosei Tomita
Kazuko Sawada
Rihoko Yoshida
Banjo Ginga
Kenichi Ogata
Keaton Yamada
Nobuyo Tsuda
Hiroshi Ôtake
Isamu Tanonaka
Keiichi Noda
Kōko Kagawa
Akira Kamiya
Kazuko Sugiyama
Toru Furuya
Ryoichi Tanaka
Noriko Ohara
Jane Val
Daniel Gall
Pierre Guillermo
Michel Gatineau
Jean-Claude Michel
Jacques Ferrière
Marcelle Lajeunesse
Jacques Berthier
Marc de Géorgi