Narumi Ioroi is an exorcist who serves as Kochin, one of the Twelve Guardians. He was born as the first son of the Ioroi Main Family and was initially destined to become the next head of the household. During his childhood, he was physically weak and lacked strong spell power, which led to him being bullied by other boys. Despite these early disadvantages, he overcame them through determination and rigorous training to become a powerful exorcist.

He is a large, muscular man with blond spiky hair, a beard, and dark skin, typically wearing a long black and yellow suit. His personality is serious, focused, and highly principled, driven by a strong belief in the sacred duty of an exorcist to fight and triumph against the Kegare, or impurities. He is motivated by a deep sense of responsibility and honor, and he places the protection of others above his own well-being. He is also a kind and caring person who genuinely concerns himself with his comrades and the people he defends. He often acts as a mentor to younger exorcists, offering guidance drawn from his extensive experience.

As one of the Twelve Guardians, his role is to protect the world from supernatural threats, particularly the Kegare. He is a skilled strategist and tactician, making him a valuable member of the Guardians, and he possesses the ability to use magic and can combine his powers with allies to create more powerful techniques. In combat, he is a proficient swordsman who wields a traditional Japanese katana with grace and precision, and he is also known to wield oversized weapons such as a hammer. He remains a firm and unwavering ally to the main protagonists throughout the story, supporting them as they face escalating dangers and uncover hidden truths. He is the father of nine children from the main family and was formerly the head of the Ioroi House.