Jōji Koizumi, who also goes by the name George, is the charismatic and complex leader of the independent fashion brand Paradise Kiss. He is an eighteen-year-old student in the fashion design department at the Yazawa School for the Arts, where his exceptional talent and distinctive vision set him apart as a promising designer, particularly with a strong inclination towards haute couture.

George is a handsome young man with a lean build, short dyed blue hair, and piercing blue eyes, a striking appearance that leads other characters to humorously compare him to an alien. His personal style is bold and extravagant, often incorporating frills, luxurious fabrics, and accessories like hats, reflecting the affluent and artistic bachelor lifestyle he leads from his loft apartment, which the group uses as their atelier. He is known to drive a vintage Jaguar, and his comfortable financial situation is funded by his wealthy father.

The circumstances of his birth have a profound influence on his character. He is the illegitimate son of a powerful corporate CEO, Joichi Nikaido, and a former model named Yukino Koizumi, who was his father's mistress. Despite the financial support that grants him a life of luxury, George grew up in the emotional absence of his father, with his mother having a passive and immature personality. This upbringing instilled in him a deep-seated disdain for women who are dependent on men and who prioritize romance over their own ambitions. His mother dryly observes that despite his resentment, George strongly resembles his father in both appearance and mannerisms.

In personality, George is a consummate artist who oscillates between being charming and cold, charismatic and rude. He possesses an unparalleled creativity and a unique worldview, but his ideals are often fantastical and resistant to compromise with reality, which makes his elaborate designs difficult to commercialize. He is self-centered, speaks his mind without concern for others’ feelings, and has a manipulative streak, using his charm and intellect to get what he wants. He can be hot and cold with those close to him, including his friends and lover, and his bluntness often comes across as heartless, especially when he chastises others for failing to live up to his ideals. Despite these flaws, he genuinely cares for his inner circle; for instance, he was the one who encouraged his childhood friend Isabella to embrace her identity as a woman.

George's primary motivation is his art. To him, fashion design is the purest form of self-expression, and he creates without concern for trends or commercial success. This passion drives him to lead Paradise Kiss, the brand he founded with his schoolmates Miwako, Arashi, and Isabella. His role in the story is catalyzed by his discovery of Yukari Hayasaka, a high school student he recruits to be the model for his collection at the school's fashion show. He views Yukari as his muse, and his relationship with her becomes a central pillar of the narrative. He aims not just to dress her, but to force her to confront her own lack of conviction, pushing her towards autonomy and self-responsibility.

Key relationships further define him. He shares a deep, long-standing bond with Isabella Yamamoto, a fellow student and a transgender woman, for whom he sewed his very first dress as a child. He is the leader of the Paradise Kiss collective, working alongside the punk rocker Arashi Nagase and the childlike Miwako Sakurada. His most significant romantic relationship is with Yukari, which is intense and complicated, serving as a catalyst for both characters’ development even though it ultimately ends.

Over the course of the story, George faces the limitations of his perfectionism when his designs fail to find a commercial market, leading to the disbandment of Paradise Kiss. This confrontation with reality, however, does not break his spirit but instead directs his path. After graduating, he chooses to leave Japan for Paris to formally study haute couture, funded by his father. His talent eventually finds its true expression on the global stage, as he achieves success by designing costumes for Broadway productions.

George's notable abilities lie almost entirely in his genius for fashion design. Since elementary school, he has demonstrated a remarkable proficiency for creating clothes, with a particular gift for the intricate craftsmanship and artistry of haute couture. He has a flawless eye for aesthetics and a clear creative conviction that makes him a natural leader and a respected, if intimidating, figure within his school.