The Gravity Curtain is a powerful generator that controls gravity made that was originally part of an experiment, likely involving a great war. However, the device was too complex to control and caused an entire landmass to be isolated by a giant tornado and gravity field, creating Machine Island. It is powered by three power stations scattered around the island. There is also the Graviton Reactor that links to the energy harnessed by the Gravity Curtain, one of which powers the Iron Kaiser. When the power reaches a critical state, it can destroy an entire planet.
It is unknown when the Gravity Curtain was activated, but after several years it started to show signs of overloading and the Skull Force was sent to deactivate it. With the Death Caprice Squad and Tsubasa Yuki the only survivors, they manage to power down two of the three stations, but with the activation of the Iron Kaiser the Gravity Curtain started to spiral out of control making it impossible to power down. The Death Caprice Squad had the Mazinkaiser SKL drag the Iron Kaiser to the core of the Gravity Curtain and with the colliding power cells plus the Inferno Blaster, the Gravity Curtain was destroyed.