The Rainbow Mask is the first of the Black Cross Army Masked Monsters under Sun Halo Mask. Though an independent agent at first, the Black Cross Führer required him to work under the general due to his return.
Rainbow Mask was in charge of protecting a fortress used by the Black Cross for their attacks, including a special "rainbow barrier" constructed to protect their property and men. With Sun Halo Mask leading, he partook in a scheme where the Gorenger were lured out, with four of them ambushed by Zolders disguised as EAGLE soldiers while Shinmei and Variblune attempted to attack the fortress on their own. After being greeted by Rainbow Mask in a vision, a grappling hook grabs Variblune forcing Aorenger to abandon it where he is soundly defeated by the Masked Monster. With the Gorenger's flying fortress in hand, Rainbow Mask and Sun Halo Mask use it to rampage through Tokyo, destroying power plants and other property.
However after regrouping, Shinmei re-sieges the fortress, entering in and retaking Variblune before blowing up the receiver controlling the rainbow barrier allowing for him to attack the zone with ease. When the Gorenger confront him, he tries to run away before Aorenger uses a homing arrow to attack him before the team finishes Rainbow Mask off with Gorenger Storm.
Modus and Arsenal
Rainbow Mask utilizes various means of attack, including illusions and clone copies to avoid attack, a rainbow beam and rainbow-streamer bombs and the creation of a special rainbow fire to the ground.