Nanaue, also known as King Shark, is a towering humanoid shark with a massive, muscular build. His body is torpedo-shaped, tapering at both ends, with dark blue skin on his back and sides and a pale white underside. He has a short, sharply pointed conical snout, and his mouth is filled with multiple rows of large, serrated teeth designed for tearing through flesh and bone. Though initially clad in an orange Belle Reve prison uniform, he later dons a stonewashed denim bib outfit.

Despite his fearsome appearance and immense strength, Nanaue has the mind of a child. He is simple-minded, often speaking in short phrases, and driven largely by his instincts—particularly his insatiable hunger. Though he can be terrifying in battle, tearing through enemies with his claws and fangs, he is also a surprisingly innocent and affectionate creature. He forms strong emotional bonds, particularly with Harley Quinn, whom he trusts and protects fiercely.

Nanaue's curiosity and loyalty make him endearing, though his lack of understanding often leads to unintended chaos. While he is a valuable asset to the Squad, his impulsive nature especially when it comes to food often puts him and his team in difficult situations.