The Byakou (ビャコウ, Byakō?) is Thymilph's personal Gunmen. It is stored within the Dai-Gunzan's hangar bays and serves as Thymilph's secondary means of combat if Dai-Gunzan is somehow incapable of doing the job.
The Byakou's body resembles a white skull with a sharp chin and a smaller face protruding out of its forehead. The shoulders and thighs of the mecha are spearhead-shaped, and spearheads are also attached to its arms.
Armaments and capacities
Its main weapon is a polearm called the Alkaid Glaive, which can emit energy from its tip to increase its power or release a powerful beam attack ("Condemn Blaze"). Unlike the personal Gunmen units fielded by the other Generals, the Byakou was never shown to transform, although it presumably does have some form of alternate mode.
Role in the show [SPOILERS]
The Byakou first saw deployment during Team Dai-Gurren's second attack on Dai-Gunzan. With his flagship immobilized while Lagann attempted to take control of it, Thymilph prepared to enter the battle personally by piloting the Byakou. It ambushed Kamina's Gurren by firing its Condemn Blaze attack from below Dai-Gunzan's deck. With the Enkidu providing backup, Thymilph's mecha was able to overwhelm its foe, culminating in the Byakou running its spear through Gurren's cockpit - and by extension, its pilot.
The Byakou apparently withdrew or was knocked off of Dai-Gunzan when Simon went berserk at the apparent death of Kamina, as it was next seen charging at the commandeered flagship in a final attempt to retake or destroy Dai-Gunzan. Surprisingly, Kamina revealed himself to be alive, allowing for the formation of Gurren Lagann. The combined Gunmen easily defeated Thymilph's remaining soldiers and deflected the Byakou's Condemn Blaze with its hand; following this, the Byakou became the first victim of the "Giga Drill Break" technique, which completely obliterated both the Gunmen and its pilot.
The Byakou was the last enemy defeated by Kamina, who finally succumbed to his wounds shortly after destroying Thymilph.
The Byakou's name is based on Byakko, the White Tiger of the West, one of the Four Symbols of the Chinese constellations in Japanese neme.