The Rouei was originally conceived as alternate equipment set for the STH-05 Hyakuren. Teiwaz’s Development Department promoted trial production of the suit, and its first deployment in live combat came when Tekkadan first descended to Earth and Naze Turbine sent out two Rouei to provide support. These two units were converted from Turbines’s Hyakurens, including the STH-05/AC Amida's Hyakuren, with the resulting Rouei piloted by Lafter Frankland. This conversion avoided implicating Teiwaz as the Hyakuren is often seen as the group's symbol. The two Rouei ended up leaving remarkable ground combat data. Based on that data, the Rouei, which had achieved lighter armor than the Hyakuren, was later officially adopted as a mass production, high mobility machine.

Besides high mobility, the Rouei also excel in combat under gravity, this is in contrast to the Hyakuren which shares the same frame structure but has excellent durability and endurance in prolonged combat The Rouei can also operate in space without any issues.