The aforementioned core was an orb located within its head. Like other biological Teigu, it was able to regenerate if damaged, unless its core was destroyed. Koro could also grow large, muscular arms and furiously unleash a volley of punches. It ferociously attacked enemies by devouring them. When ordered, it had the ability to grow to a much larger size, increasing its strength and durability. Hekatonkheires, nicknamed as Koro for short by its last owner, was a biological Teigu resembling a small, white dog with black eyes, ears and a nose that stands on its back legs. A dying Koro stays by Seryu's side, no longer able to regenerate due to its core suffering heavy damage, as she used a suicide bomb inside herself as her last resort in an attempt to kill Mine, taking out the entire valley, along with herself and Koro. As both Seryu and a recovered Koro attempt to attack from both sides, Mine suddenly bifurcates Koro with her trump card, destroying its core, and Seryu is also cut in half by Mine, avenging Sheele. While Koro sits out the battle to recover from Mine's shots, Seryu is forced to face Mine herself and manages to beat her insanely with her lighting-speed punches, leaving Mine mortally wounded and nearly dying. During the second battle between Mine and Seryu, Koro attempts to attack Mine, but it suffered a large amount of damage by Mine's Pumpkin due to her increased power, since the more danger she was in, the more powerful her Pumpkin would be, as she blasts him apart with every shot, rendering it unable to fight back as she keeps shooting at Koro until his core is shown, which causes Seryu to once again unleash its trump card, Berserker, but Mine manages to anticipate its roar by putting on her earplugs, negating its sound. Tatsumi faces off against Suzuka while Mine prepares to fight Seryu and Koro. Koro appears later as Seryu attacks Mine and Tatsumi at the valley, who narrowly escape. Later, after Chelsea was killed and had her head sliced off by Kurome, Seryu had Koro devoured her body. Since then, Mine vowed to get vengeance upon Seryu and Koro to avenge Sheele. Mine cries out to Sheele, who is able to use Extase to emit a blinding light as her trump card, allowing Mine to flee as Koro then devours Sheele, killing her instantly. The shot came from a gun that was implanted in Seryu's mouth.

Sheele manages to cut off Koro's arms to save Mine. Unleashing a deafening roar, Mine is stunned by its roar and Koro quickly grabs Mine and attempts to crush her bones. Facing a dire crisis, Seryu uses her last resort by ordering Koro to go activate its trump card: Berserker. Sheele succeeds in cutting off both of Seryu's arms, only to discover that Seryu also has guns implanted into her arms. As Mine blasts Koro with her Pumpkin, it regenerates from all of her attacks so long as its core is intact. Seryu engages Sheele while Mine fights against Koro. As Mine and Sheele run through the park, they are ambushed by Seryu, as she vows to take her vengeance over her mentor, Ogre. Seryu Ubiquitous receives Koro when she became a member of the imperial police.

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