When using Koro on the Minks, he wears a hazmat suit and wears a glass helmet around his head. His mouth contains puffed lips and pointed teeth like any fish-man but while in his mammoth form he has square teeth. He carries a pair of tusks around his neck which are actually sheathes containing his scythe-like blades. He has two piercings in his right ear, and wears spiked pauldrons on his shoulders. He has bloodshot orange eyes and a veined forehead. During his fight against Inuarashi, this Jolly Roger was destroyed after being pierced by the latter's final attack. He wears a light brown (darker in the anime) sleeveless feathery coat similar to Kaidou with spiked pauldrons on his shoulders, circled by a belt bearing his crew's Jolly Roger. His blond hair is worn in a ponytail and a pair of long braids. He wears a metallic jaw mask that seemingly disappears when he transforms into his mammoth form, and has a pair of horns on each side of his head. While still being immensely muscular, Jack's limbs are disproportionately small when compared to his enormous torso (though their size is greatly increased in the anime, especially his arms).

Unlike the majority of fish-men, his pale skin is identical to that of a human, making it easy to mistake him for one.

Jack is a giant grouper fish-man of massive stature, dwarfing his crewmates and standing taller than even his governor-general Kaidou.

Kingdom by Jack Hight