"Kyoukaisenjou no Horizon: The Animation" features a diverse cast of characters set in a fantastical world where nations are represented by students. The main protagonist, Horizon Ariadust, is a mysterious girl with a significant role in the story, while Tenzou Kisaragi, her loyal protector, navigates the complexities of their relationship and the political landscape. Other notable characters include Masazumi Saionji, a skilled strategist, and Neshinbara, a passionate writer. Each character brings unique abilities and backgrounds, contributing to the intricate plot that intertwines personal struggles with larger conflicts among the various factions in the series.