Izumo Ikusabe is a student at the Rotsgard Academy and becomes one of the pupils of the protagonist, Makoto Misumi, who is known at the academy by the alias Raidou. He is a young man of a slender but athletic build; after beginning his training under Makoto, he develops a more muscular, tanned body with several scars on his arms, a significant change from his original pale and less physically developed frame.

His background is deeply tied to the political history of the human city of Lorel. Izumo is a member of the Ikusabe family, which originated as a branch family of the main Osakabe household from the region of Kannaoi. Several hundred years prior, the Ikusabe were cast out by the Osakabe family, leading them to settle in the region of Naoi, where they serve the governing Kahara family as a military house, functioning much like samurai and ninjas. This conflict has left a lasting impact on Izumo; the main Osakabe family has historically mocked the efforts of the Ikusabe, and in the present day, Izumo finds himself in a complex political situation involving an engagement to Iroha, a princess of the Osakabe family.

Motivated by a desire to resolve his family's standing and forge his own path, Izumo is dedicated to increasing his personal strength. At the academy, he and his classmates are deeply impressed by the overwhelming power and unique teaching methods demonstrated by Makoto and his undead servant, Shiki. As a result, Izumo chooses to join their special class, seeking to gain abilities that go beyond the standard curriculum. He relies heavily on Shiki as a mentor and possesses a pragmatic view of his training, understanding that his academy life is far from over and that he must take an active role in determining his future.

Within the story, Izumo serves as one of the more prominent background students in Makoto's class, often representing their collective growth and the impact Makoto has on the world. His key relationships are with Makoto, whom he respects as a teacher, and with Shiki, who provides direct academic and magical guidance. His classmates, including figures like Dia, are his close peers. His personal life is further complicated by his political engagement, which is a significant factor in his development as he learns to reconcile his personal wishes with his family's expectations.

In terms of development, Izumo undergoes a notable transformation in both philosophy and skill. Initially a mage with a slender build, he comes to understand the critical importance of physical conditioning to complement magical ability, a core tenet of Makoto's training regimen. This change is reflected in his altered appearance, as his body becomes tanned and muscular.

Izumo is a capable mage who specializes in wind-based magic. Facing the practical problem of slow spell activation due to lengthy incantations, he develops several unique combat skills to overcome this weakness. One such skill is Maneuver Aria, which allows him to divide a long incantation into several parts and then combine them to activate the spell, enabling him to perform arias even while moving. Another is Irregular Reutilization, a technique that lets him repurpose the residual mana from spells that have already been cast and normally would have dissipated, using it to fuel his next spell. He is also capable of activating multiple spells at once, showcasing his advanced control over his magical power. Furthermore, he possesses the ability to speak multiple languages, which allows him to understand Makoto, who primarily uses Japanese.