Koimura, known as the Steel Elementalor, serves within a coalition dedicated to preserving equilibrium among elemental powers. He stands against Lord Shiki’s faction during the clash sparked by Shiki’s attempt to free his daughter, Shiohisa—an act risking worldwide destabilization. As a wielder of steel, he commands mastery over metallic elements, channeling them in combat with tactical precision.

Aligned with Kagura and fellow Elementalors, Koimura aids in liberating Asami and thwarting Shiki’s ambitions. His contributions emerge during pivotal skirmishes against Shiki’s forces, though his strategic role within the team remains concise. The narrative positions him alongside peers like Tsuyuha, Sai, and Shizuku, though their collective synergy receives minimal elaboration.

Koimura’s origins, personal drives, and evolution remain undisclosed, with his presence confined to the OVA’s core conflict. His story extends no further into supplementary media or alternate installments.