In a world where 'Irises' signify unique abilities, high schooler Tooru Mizushima stands out as an 'Iris Zero' without these powers. Bullied and trying to blend in, his life takes a turn when the popular Koyuki Sasamori recruits him to help find the next student council president using her Iris ability. Reluctant at first, Tooru's journey unfolds as he uncovers mysteries and forms new connections, embracing his keen deductive skills along the way.