Shin Getter Robo vs Neo Getter Robo (真ゲッターロボ対ネオゲッターロボ) is an anime OVA series based off the works of Go Nagai. It was released in four episodes on four DVDs from December 2000 to June 2001.
Shin Getter Robo vs Neo Getter Robo draws heavily from Nagai's manga Getter Robo Go. An anime adaptation of Getter Robo Go was made in 1991, but was toned down, losing most of Nagai's famous style. Neo Getter Robo features much more faithful versions of Nagai's characters, but with a new plot and new Getter. Because of this, many consider Neo Getter Robo to be a redemption for the Getter Robo Go anime. (Wikipedia)