"Iris Zero" is set in a world where nearly everyone possesses a unique ability called an "Iris," which grants them special powers such as seeing lies, predicting danger, or reading emotions. These abilities manifest during childhood and vary widely in strength and utility. However, the protagonist, Toru Mizushima, is an "Iris Zero," one of the rare individuals born without an Iris. This makes him an outsider in a society that heavily relies on these abilities, and he has learned to navigate life by observing and analyzing others to compensate for his lack of supernatural power.

Toru's life takes a turn when he is approached by Koyuki Sasamori, a popular and cheerful girl with the Iris ability to see lies. Koyuki seeks Toru's help in solving a mysterious incident involving her friend, who has gone missing. Despite his initial reluctance to get involved, Toru's sharp observational skills and logical reasoning prove invaluable in uncovering the truth. This partnership marks the beginning of their collaboration, as they tackle various mysteries and social issues within their school and beyond.

The narrative explores themes of identity, societal expectations, and the value of human connection in a world dominated by supernatural abilities. Toru's lack of an Iris forces him to rely on his intellect and empathy, making him a unique and compelling protagonist. Koyuki, on the other hand, struggles with the burden of her Iris and the pressure it places on her relationships. Together, they form a balanced team, with Toru's analytical mind complementing Koyuki's emotional insight.

As the story progresses, the duo encounters a range of characters, each with their own Iris abilities and personal struggles. These include Shou Harasawa, a boy with the ability to see danger, and Asahi Hinomori, whose Iris allows her to see the future but at a great personal cost. The series delves into the complexities of these abilities, showing how they can be both a blessing and a curse, and how they shape the lives of those who possess them.

The plot is driven by a series of interconnected mysteries, ranging from school-related incidents to larger societal issues. Each case reveals more about the characters and the world they inhabit, gradually uncovering deeper layers of intrigue and conflict. The narrative maintains a balance between episodic storytelling and an overarching plot, keeping the reader engaged with both individual cases and the broader mysteries surrounding the Iris phenomenon.

"Iris Zero" combines elements of mystery, drama, and slice-of-life, creating a thought-provoking and emotionally resonant story. The series examines the impact of supernatural abilities on human relationships and societal structures, offering a nuanced exploration of its central premise. Through its well-developed characters and intricate plotlines, "Iris Zero" presents a compelling narrative that appeals to fans of both mystery and character-driven storytelling.