Gravion (超重神グラヴィオン, Chōjūshin Guravion?, lit. Super Heavy God Gravion) is an anime television series produced by Gonzo. It aired in Japan from October 7, 2002 to December 16, 2002 and ran for 13 episodes. In 2004, Gravion Zwei (超重神グラヴィオンZwei, Chōjūshin Guravion Tsuvai?, "Zwei" is German for "two") was released and aired from January 8 to March 25 in Japan, running for twelve additional episodes, answering the questions generated from the first series.

Both Gravion and Gravion Zwei are created and directed by Masami Obari and is released in the United States by ADV Films.

Source: Wikipedia