Rainbow

In most cases, Rainbow is delightful and enjoys jokes and pranks, but you should never take this for granted. Once it feels you have gone too far, it will squirt a shower of special pigment that will not come off for a whole month.

As Rainbow is a CUB inspired by a marine species like Shimmer and Seeshell, it makes the three of them become a close trio of friends among all CUBs. Rainbow would give Shimmer a new coating once in a while and relax lying on Seeshell in leisure time.

Originally a robotic artistic education assistant at the Center of Basic Public Education, Rainbow is equipped with 127 pigments, 28 types of paintbrushes, and 7 types of paint sprayers. After being modified into a Combat Unit Booster by Leonie, Rainbow is able to sweep the battlefield with splashes of color alongside Kaleido's Beam Gunlance.

Rainbow's bowknot was a gift from the kids at the Center of Basic Public Education when it left there, now its most treasured ornament that it refuses to take off even on the battlefield. However kind and pleasant Rainbow is, if any enemy dares dirty its bowknot, it will end battles like a devastating hurricane.

Presumably affected by its owner, among all the CUBs Rainbow is the one most into "making friends." To the staff of the Science Council, it is common to see Rainbow building bridges with other CUBs in the maintenance room. And one day, when the staff of the Science Council returned to the maintenance room after a vacation, they immediately realized that they had forgotten to enable hibernate mode on the CUBs before they left. The maintenance room was turned into a "party room" with every inch splashed with colors by Rainbow. All the CUBs were so high that they were parading around the room, celebrating. This merrymaking lasted until the Science Council called in the CUBs' owners to calm them down.