Melon is a major antagonist and a character of complex, tragic origin. He is a hybrid, born from the union of a leopard mother and a gazelle father, which places him in a unique and tormented position within a society deeply divided between carnivores and herbivores. Physically, he possesses the horns of a gazelle but has the jaw, claws, and feline eyes of a leopard. To navigate the world and conceal his predatory heritage, he typically wears a surgical mask in public and keeps his eyes narrowed to hide his slit pupils. As he ages, leopard spots gradually emerge across his body, which he chooses to cover with an intricate network of tattoos shaped like melon leaves.

Melon's personality is defined by cunning, sadism, and a chilling lack of remorse, traits that mark him as a sociopath. He is highly deceptive, using a facade of charm and empathy to manipulate others for his own gain, often leading them to serious injury or death. His knowledge as a psychologist aids him in this manipulation, allowing him to understand and exploit the vulnerabilities of those around him. As the new boss of the Shishigumi, a gang of lions, he rules with cruelty and harshness, a stark contrast to previous leaders. He enforces bizarre and cruel rules, such as severely limiting his subordinates' meat intake, and shows no respect for their lives. Despite his cruel exterior, Melon is driven by a profound inner void. Due to his hybrid biology, he cannot taste food; everything, whether plant or meat, tastes like sand to him. This lack of sensation extends to other appetites, leaving him in a state of perpetual numbness. The only way he can feel truly alive is through the experience of pain, a sensation he actively seeks out, most notably during the excruciating process of getting his tattoos.

Melon's role in the story is that of the primary antagonist in the final arc, often referred to as the Revenge of the Love Failure arc. He is first introduced posing as a psychotherapist specializing in large herbivores, a cover he uses to gain the trust of elephant patients before murdering them and stealing their tusks for ivory. His path crosses with the protagonist, Legoshi, during an operation led by the horse, Yafya, to capture him. Despite Legoshi showing him empathy due to their shared status as hybrids, Melon responds with violence, shooting him and establishing a bitter rivalry. He later becomes a part-time university history teacher, where he encounters Haru, a dwarf rabbit and Legoshi's love interest. In a strange turn, Haru is one of the few beings who does not recoil from his hybrid nature, and she inadvertently becomes the first person to make him feel a genuine sense of appetite, specifically the desire to eat her. This creates a twisted and dangerous connection between them.

Key relationships define much of his interaction with the world. His relationship with Legoshi is one of a dark parallel; both are hybrids struggling with their conflicting natures, but while Legoshi seeks harmony and self-control, Melon surrenders to chaos and violence. He views Legoshi's empathy as a weakness to be mocked and exploited. His relationship with the Shishigumi is purely transactional and abusive, using them as tools while treating them with contempt. His connection to Haru is the most anomalous, as she awakens in him a desire he had never truly experienced, creating a fixation that is both predatory and strangely vulnerable.

Melon's development is rooted in a deeply traumatic childhood. He was bullied mercilessly by both herbivore and carnivore children for not fitting into either category, and he committed his first murder at the age of nine by throwing his tormentors from a rooftop. His home life was equally destructive. Raised by his leopard mother in a room decorated like a fairy tale, he longed for her love but was ultimately met with a horrifying revelation. When he asked about the meaning of his name, his mother compared him to a melon—neither fruit nor vegetable but delicious—and admitted that his taste reminded her of his father, a gazelle she had eaten. This traumatic confession shattered any remaining innocence, and Melon killed her in a fit of rage, framing her death as a home invasion. This event caused him to completely shut off his heart, believing all love to be a fabricated lie.

Melon possesses several notable abilities that make him a formidable threat. His hybrid physiology grants him the heightened senses, agility, and physical prowess of a carnivore, including sharp fangs and claws, combined with the more delicate frame of a herbivore, which can be deceptive. He is highly intelligent and a master of psychological manipulation, using his charm and a false sense of empathy to disarm his victims. He is also an expert in disguise and deception, seamlessly blending into herbivore society. In combat, he is resourceful and ruthless, often employing a firearm or a cleaver, but he is also capable of hand-to-hand combat, relying on his natural weapons and fighting instincts. His masochism grants him an unnerving tolerance for pain and blood loss, allowing him to continue fighting long after receiving wounds that would incapacitate others.