Issei Ariga is a tall, thin man with medium-length black hair and gray eyes who works as a hairdresser and beautician. His youth was marked by a deep passion for hair and an unwavering commitment to his customers, channeling all his energy into becoming an outstanding stylist. While his methods of customer service are notably unusual and his personality is undeniably quirky, his undeniable skill and expertise earned him a reputation as one of the best in his profession.

The defining event of Ariga's life was the murder of his younger sister, Sanae, at the hands of a mysterious and beautiful woman. This tragic loss became the driving force behind all his actions, replacing his simple passion for hairdressing with a burning obsession for revenge. Using strands of hair as his only clues, he spent years tracking the killer, committing the appearance of her hair to memory. His quest led him to confront Aronis of Pride when she arrived as a guest at his salon. Instantly recognizing her as his sister's murderer, Ariga attacked her in a fit of rage. However, he was completely overpowered by Aronis, who forcibly transformed him into a Nevestigma Chrysalis against his will.

Following his transformation, Ariga found himself pursued by a woman named Tanaka Yasuko. To escape her, he fled and joined the ranks of the Execution Squad, known as the Shoshidai, even entering cold sleep to suppress his Chrysalis state. However, he found the organization's dangerous missions to be tedious and frustrating, leading him to ultimately desert and return to his former life as a hairdresser. Back at his salon, Ariga experienced a dramatic reunion with both Yasuko and Aronis. He attempted to face Aronis in battle once more but found himself utterly captivated by the magnificent beauty of her hair, rendered completely unable to fight. In the end, it was Yasuko who saved him, an act that taught Ariga to accept her as an ally and to find a new sense of acceptance and camaraderie.

Ariga is characterized by his blunt demeanor and unshakable focus on avenging his sister. His devotion to hairdressing borders on obsession, and he values the art of the perfect cut as much as he values justice. His hairstyling techniques are precise and refined, using criticism as a tool to achieve perfection. Even as a Chrysalis, this core aspect of his identity remains, and he ultimately chooses to return to his salon, rediscovering his purpose. His journey is defined by a painful conflict between his quest for revenge against Aronis and his deep, instinctive admiration for beautiful hair, as well as a gradual shift from stubborn solitude to learning to accept help and connection from others like Yasuko. In his Chrysalis form, he possesses enhanced healing abilities that add to his physical capabilities.