ChouRyuuJin is part of GGG's Mobile Unit, he is formed from the Symmetrical Docking, also called the Lateral Combination (左右合体 - Sayuu Gattai, this combination name was originally used by Ultra Raker) of G.B.R.-02 HyouRyuu and G.B.R.-03 EnRyuu. He can then theoretically combine with G.B.R.-05 ShouRyuu to form ShouChouRyuuJin, although the combination was never seen used in the GaoGaiGar medias.
ChouRyuuJin is the result of HyouRyuu and EnRyuu's Symmetrical Docking, when their SympaRate have reached 100%. He is mostly a protecting specialist with the Mirror Shield as his chestplate and usage of the Eraser Head tool to diffuse explosions (and the only Brave who can properly use the tool with his Power Crane and Ladder as support). During space battles, ChouRyuuJin is equipped with a pair of boosters called the SP Pack on his shoulders for easy maneuvering. When required, he can also have the supply ship Climber-1 attach onto his back for extra power and thrust.
Amongst the Ryuu family, ChouRyuuJin has the most serious battle damage record, being left in heavily damaging or even near-death status multiple times, which includes when intercepting EI-16's long-range mortar blast, combatting Zonderians Primada and Polonaise as EI-29 and EI-28, after using Projectile-X in the battle with EI-01, falling down on Earth from space 65 million years ago after an ES portal warp, split in half by Repli-Star GaoGaiGar and, as HyouRyuu and EnRyuu, heavily damaged after using the Supernova in the battle with P-Vater.