"Aikatsu on Parade!" is a crossover anime and manga series that brings together characters from various entries in the "Aikatsu!" franchise, a multimedia project centered around idol culture. The narrative revolves around the concept of a "Dream School Festival," an event where idols from different dimensions and timelines gather to collaborate and showcase their talents. The story begins with Yume Nijino, a cheerful and aspiring idol from the main "Aikatsu Friends!" series, who is transported to a mysterious theater called the Aikatsu Palace. There, she encounters a magical rabbit named Usagi, who serves as a guide and introduces her to the concept of the Dream School Festival.

The Aikatsu Palace acts as a hub where idols from different worlds, including characters from "Aikatsu!", "Aikatsu Stars!", and "Aikatsu Friends!", converge. Each idol brings their unique style, personality, and experiences, creating a vibrant and diverse ensemble. The festival is structured around various performances and challenges, where idols form temporary units and compete to deliver the most captivating shows. The overarching goal is to collect "Dream Stars," special items that grant the power to make dreams come true, emphasizing themes of teamwork, perseverance, and self-expression.

Key characters include Yume Nijino, whose enthusiasm and determination drive much of the story, and her friends Aine Yuuki and Mio Minato from "Aikatsu Friends!", who provide support and camaraderie. Characters from other series, such as Ichigo Hoshimiya from "Aikatsu!", Yuzu Nikaido from "Aikatsu Stars!", and others, also play significant roles, contributing their unique talents and perspectives. The interactions between these characters highlight their growth as idols and individuals, as they learn from one another and overcome challenges together.

The plot is episodic, with each episode or chapter focusing on a specific performance or event within the Dream School Festival. These segments often explore themes of friendship, creativity, and the pursuit of dreams, while also showcasing the franchise's signature blend of music, fashion, and idol performances. The series maintains a lighthearted and optimistic tone, with occasional moments of drama and introspection to add depth to the characters' journeys.

As the story progresses, the idols face increasingly difficult challenges, culminating in a grand finale where they must unite their strengths to achieve a shared dream. The resolution emphasizes the importance of collaboration and the belief that dreams can be realized through hard work and mutual support. "Aikatsu on Parade!" serves as both a celebration of the franchise's legacy and a platform for introducing new characters and ideas, making it accessible to both longtime fans and newcomers.