Kisshu, also known as Kish or Quiche in some localizations, is a primary antagonist in the Tokyo Mew Mew series. He is a sixteen-year-old alien whose race originally lived on Earth but was forced to flee to a barren, hostile planet after a natural disaster. Generations later, with their new home becoming uninhabitable and their people suffering, Kisshu, along with his comrades Pai and Taruto, is sent back to reclaim Earth by eliminating the human population he blames for destroying the planet.

Physically, Kisshu has a youthful and slender build, standing about the same height as the protagonist, Ichigo Momomiya. He has very pale skin, dark green hair cut short in the back with longer strands tied in front of his pointed, elf-like ears, and sharp canine teeth. His most striking features are his bright golden-yellow eyes with slit pupils. His attire is characteristic of his race, typically consisting of a black, high-collared shirt with puffy sleeves and a brown, midriff-baring vest, paired with black baggy shorts, dark red wrist and shin bandages, and boots.

Kisshu is defined by a complex and often contradictory personality. He initially presents himself as playful, carefree, and mocking, treating his mission and battles with the Mew Mews as an amusing game. However, this lighthearted facade masks a deeply cruel and sadistic nature. He takes great pleasure in causing humans both physical and mental anguish, and he is ruthless in his methods, using monsters called Chimera Animas to accelerate environmental destruction. Despite his impulsiveness and tendency to act on emotion, he is intelligent and clever, often finding ways to turn mistakes to his advantage.

His primary motivation is to save his dying people and reclaim Earth for them. This mission becomes increasingly intertwined with his obsessive infatuation with his main enemy, Ichigo Momomiya, the leader of the Tokyo Mew Mews. Upon first meeting her, he is drawn to her feline charm and forcibly steals her first kiss, initially viewing her as an entertaining toy. Over time, this attraction deepens into an all-consuming, possessive love. He becomes violently jealous of Ichigo's boyfriend, Masaya Aoyama, repeatedly attempting to kill him so Ichigo will have no one else but Kisshu. His love is obsessive and possessive; when Ichigo rejects him, his feelings turn to rage, and he threatens to kill her if he cannot have her.

As the series progresses, Kisshu's character undergoes significant development. His genuine love for Ichigo is revealed to be more than a simple obsession, and he demonstrates a deep, if twisted, capacity for strong emotion. In the final arc, when Masaya is revealed to be the malevolent Deep Blue, Kisshu makes a pivotal choice. He turns against his own leader to protect Ichigo, a decision that leads to him being fatally wounded. He dies in Ichigo's arms after a final declaration of love. Following Deep Blue's defeat, Kisshu is revived by the power of the Mew Aqua. In the end, he accepts that Ichigo's heart belongs to another, wishes her happiness, and returns to his home planet with his comrades after stealing one last kiss from her.

As an antagonist, Kisshu is the first alien to confront the Mew Mews and serves as a recurring threat throughout the story. He is a capable fighter whose notable abilities include flight, teleportation, and underwater breathing, common traits of his species. His primary weapons are a pair of sai, which he calls Dragon Swords, and he is proficient in using them to channel energy blasts and lightning in combat.