"Wonder Egg Priority" centers on Ai Ohto, a socially withdrawn 14-year-old girl who struggles with the suicide of her close friend, Koito Nagase. One night, Ai encounters a mysterious entity that leads her to purchase a "Wonder Egg," a strange egg that transports her to a surreal dream world. In this world, Ai must protect a girl from monstrous manifestations of trauma and despair. Each girl Ai saves represents someone who has taken their own life, and by helping them, Ai hopes to bring Koito back.

As the series progresses, Ai is joined by three other girls—Neiru Aonuma, Rika Kawai, and Momoe Sawaki—each grappling with their own personal traumas. Neiru, a stoic and enigmatic girl, seeks to save her sister; Rika, a former idol, struggles with guilt over her friend’s suicide; and Momoe, who is often mistaken for a boy, faces challenges related to identity and societal expectations. Together, they navigate the dream world, confronting increasingly complex and harrowing scenarios that mirror their real-world struggles.

The narrative delves into themes of mental health, identity, and the impact of societal pressures on young people. The dream world serves as a metaphor for the characters' internal battles, with the monsters representing various forms of abuse, neglect, and trauma. As the girls fight to save others, they also confront their own unresolved pain and begin to heal.

The story takes a darker turn as the lines between the dream world and reality blur. The girls discover that their actions in the dream world have consequences, and the true nature of the Wonder Eggs and the entities controlling them is gradually revealed. The series builds toward a climactic confrontation that challenges the characters to face their deepest fears and make difficult choices about their futures.

"Wonder Egg Priority" combines psychological drama with elements of magical realism, creating a narrative that is both emotionally resonant and thematically rich. The characters' journeys are interwoven with a broader exploration of the societal factors that contribute to mental health struggles, making it a thought-provoking and impactful series.