"Dia Horizon (Kabu)" is a multimedia project that includes an anime series, games, and other related content. The story is set in a world where humanity faces extinction due to the emergence of a mysterious phenomenon known as the "Dia Horizon," a massive rift in the sky that unleashes destructive creatures called "Kabu." These creatures threaten the survival of humanity, forcing people to live in fear and isolation.

The narrative centers on a group of young individuals who are chosen to become "Horizon Keepers," warriors tasked with protecting the world from the Kabu. Each Horizon Keeper is granted unique abilities and weapons, known as "Horizon Arms," which are powered by their determination and will to fight. The main characters include a diverse cast, each with distinct personalities and motivations, who must work together to confront the Kabu and uncover the truth behind the Dia Horizon.

As the story progresses, the Horizon Keepers face numerous challenges, both from the Kabu and from internal conflicts within their group. The series explores themes of survival, camaraderie, and the struggle to maintain hope in a world on the brink of collapse. The characters' backstories and relationships are gradually revealed, adding depth to their interactions and decisions. The plot also delves into the origins of the Dia Horizon and the true nature of the Kabu, raising questions about humanity's role in the crisis and the possibility of redemption.

The anime balances action-packed battles with moments of introspection, as the characters grapple with their fears and responsibilities. The world-building is intricate, with a focus on the societal impact of the Dia Horizon and the ways in which people adapt to their new reality. The series maintains a steady pace, gradually unraveling its mysteries while keeping the audience engaged with its dynamic characters and high-stakes conflicts.