Ai Ōto is a teenage girl marked by heterochromia—one golden-amber eye and one deep blue eye—a trait that led to severe bullying and caused her to become a reclusive school refuser. She has dark blue hair styled in a tousled bob with a persistent ahoge and a yellow triangular hair clip above her left eye. She typically wears a casual yellow hoodie with a sunflower design, volleyball shorts, and chunky platform sneakers. Her life changes when she bonds with transfer student Koito Nagase, who befriends her and admires her eyes. After witnessing Koito endure bullying, Ai tries to gather evidence but freezes in fear. Koito’s death by suicide amplifies Ai’s guilt, driving her into a supernatural pact involving Wonder Eggs. By cracking open these eggs, she enters dream realms where she fights manifestations of trauma called Seeno Evils or Wonder Killers, aiming to protect other suicide victims in hopes of bringing Koito back. Her primary weapon is a four-color ballpoint pen that transforms into weapons like a club or saber; she later gains a chameleon-like companion named Leon. Over time, Ai allies with three other girls carrying their own grief: Neiru Aonuma, Rika Kawai, and Momoe Sawaki. Initially timid and self-doubting, Ai develops resolve and compassion, defending others from their fears and bridging isolation. In a final mission, she encounters a parallel version of herself who never knew Koito; that alternate Ai sacrifices herself to help revive Koito. Although Koito returns, she does not remember Ai, leaving Ai heartbroken. Ai changes schools but later resumes her egg missions, determined to save Neiru after her disappearance. Through loss and fractured outcomes, Ai transforms from passive guilt into active tenacity, persisting in her fight to protect others.