Getter Robo Armageddon ( 真(チェンジ!!)ゲッターロボ~世界最後の日, Shin (Chenji!!) Getta Robo~Sekai Saigo no Hi), often simply referred to as Change!! Getter Robo in Japan, is an original video animation released in 1998 by Bandai Visual, based on the manga and anime series Getter Robo, created by Go Nagai and Ken Ishikawa.
In Getter Robo Armageddon, Shin Getter is Professor Saotome's ultimate creation during the prologue of the story. After breaking through a group of mass-produced Getter Robo Gs, Ryoma Nagare and Hayato Jin find it inside the Saotome Laboratory along with Go "Saotome", the professor's genetically engineered "son". When the trio learns that the military has launched a nuclear warhead at the newly-formed Shin Dragon, they use Shin Getter in an attempt to stop the attack, but ultimately fail, causing a Getter Ray contamination that kills most of the planet's population. Several years later, when the story picks up again, Shin Getter is piloted by Go, Kei Kuruma (Getter teammate Benkei Kuruma's adopted daughter) and Gai. They use Shin Getter until Shin Dragon joins them willingly to fight the Invaders, at which point Ryoma, Hayato and Benkei take up the piloting duties for Shin Getter. The two Getters combine their energy to create incredible attacks, capable of destroying Jupiter and its Invader-infected moons, but Shin Getter ends up stranded in another dimension, fighting alongside Getters from other universes for all eternity. (Wikipedia)