Iris is a member of the Special Fire Force Company 8, where she serves as a sister, or nun, originally from the Holy Sol Temple. She is a young woman of sixteen years with short blonde hair and blue eyes, and her standard attire is a white habit adorned with blue lines that signify her affiliation with a Special Fire Brigade. Having grown up in the church alongside Princess Hibana, the two witnessed a fire that claimed the lives of all the other sisters, leaving them as the only survivors of that tragic incident.

In terms of personality, Iris is defined by her gentle, courteous, and deeply kind-hearted nature. Her strong religious faith drives her to want to help and support anyone in need, and she possesses a timidity that is balanced by a surprising bravery on the battlefield, often standing unfazed in the face of dangerous Infernals. While she is typically shy and prioritizes the security of others, she occasionally surprises those around her with bold words or actions and can display a childish curiosity and a dry wit, making snide remarks about her teammates. Her private nature means she tends to keep her feelings to herself, though her motivations remain rooted in her beliefs and her desire for world peace.

Within Company 8, Iris occupies a unique religious role. Her primary function is to perform the Prayer of Repose for the souls of Infernals, using a special holy book and rituals to grant them peace as they are destroyed by her comrades. This function is considered a crucial link in the fight against spontaneous human combustion, emphasizing spiritual redemption over physical combat. Although she is initially portrayed as a non-powered individual lacking any pyrokinetic abilities, she shows bravery in other ways, such as providing quick first aid and thinking quickly under pressure. She shares a strong friendship with her teammate Maki Oze and regards Princess Hibana, who was raised in the same convent, as an older sister. Her relationship with fellow company member Shinra Kusakabe evolves significantly, as she displays a special concern for his safety and a willingness to assist him in his missions, eventually developing strong feelings for him.

Iris experiences considerable development over the course of the series. Initially someone who only provided spiritual support from the sidelines, she is later revealed to be far more significant than she appears, as she is the doppelgänger of Amaterasu and is identified as the Eighth Pillar, a person who possesses the special Adolla Burst. After the emergence of the stone pillars that proved the existence of all eight Pillars, Iris awakens her own Third Generation ignition abilities, though her control over fire is weak and inexperienced, initially only able to generate small embers from her fingers. As she learns to harness this power, she develops notable defensive capabilities, including the ability to grant herself and her allies a potent protective aura of heat. This ability, sometimes referred to as the Protection or Blessing of the Evangelist, provides an unprecedented level of immunity to flames, powerful enough to negate the dangerous shockwaves produced by Shinra's own abilities. This evolution transforms her from a purely symbolic figure into an active participant with a vital role in the company's battles.