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
Duke Fleed / Daisuke Umon (voice)
Hiroya Ishimaru
Koji Kabuto (voice)
Joji Yanami
Genzo Umon / Great King Vega (voice)
Chiyoko Kawashima
Hikaru Makiba (voice)
Kosei Tomita
Danbei Makiba / General Gandal / Nuke / Whiter (voice)
Kazuko Sawada
Goro Makiba / Lady Gandal (voice)
Rihoko Yoshida
Grace Maria Fleed / Commander Marine (voice)
Banjo Ginga
Science Minister Zuril (voice)
Kenichi Ogata
Blaki / Bunta Arano (voice)
Keaton Yamada
Akira Hayashi (voice)
Nobuyo Tsuda
Hara Arano (voice)
Hiroshi Otake
Boss (voice)
Isamu Tanonaka
Mucha (voice)
Keiichi Noda
Captain Gorman (voice)
Kouko Kagawa
Commander Mineo (voice)
Akira Kamiya
Ainzu (voice)
Kazuko Sugiyama
Commander Kirika (voice)
Toru Furuya
Kane (voice)
Ryoichi Tanaka
Zuril Junior (voice)
Noriko Ohara
Princess Rubina (voice)
