"Dimension High School" is a science fiction anime that blends elements of comedy, adventure, and fantasy. The story centers around a group of high school students who are unexpectedly transported to a parallel dimension while attending a seemingly ordinary school assembly. This alternate dimension, known as the "High School Dimension," is a surreal world where academic subjects like math, science, and history are governed by bizarre, game-like rules and inhabited by anthropomorphic representations of abstract concepts.

The protagonist, Aoi Hibarigaoka, is an average high school student with a keen interest in video games. Alongside his classmates, including the studious Riko Saionji, the athletic Kakeru Shido, and the enigmatic transfer student Rei Mizutani, Aoi must navigate this strange world to uncover the truth behind their predicament. The group discovers that their presence in the High School Dimension is no accident; they have been summoned to participate in a series of challenges that test their knowledge, creativity, and teamwork. These challenges are orchestrated by the dimension's overseers, who appear as eccentric, larger-than-life figures with their own agendas.

As the students progress through the dimension, they encounter various obstacles that require them to solve puzzles, engage in intellectual battles, and confront their own insecurities. The narrative explores themes of self-discovery, friendship, and the value of education, as the characters learn to apply their unique strengths to overcome the trials they face. The stakes escalate when they uncover a deeper conspiracy tied to the dimension's existence, revealing that their success or failure could have far-reaching consequences for both worlds.

The series balances its fantastical premise with humor and character-driven moments, offering a mix of lighthearted antics and dramatic tension. The interactions between the main characters drive much of the story, as their diverse personalities and backgrounds create both conflict and camaraderie. By the end of the series, the students must confront the ultimate challenge, which not only tests their abilities but also forces them to question the nature of reality and their place within it.