OVA
Description
Gekkō Kurenai commands the student council presidency at Miyasaka High School, a role intrinsically linked to protecting the Holy Ground—a dimensionally unique site beneath the campus. Sixteen years old, he possesses jet-black hair, sharp green eyes, and favors his school uniform with a stand-up collar. He presents an aloof, intimidating presence marked by a cold, piercing gaze and a self-proclaimed genius persona. Academically brilliant and athletically unmatched, his curt, offensive manner consistently pushes others away. Yet beneath this exterior, he holds profound loyalty for his comrades, readily risking his life in their defense.

Nine years before the present, his twin brother, Hinata Kurenai, murdered their parents. This shattering event ignited Gekkō's relentless drive for power, initially driven by fear for his own survival and later by vengeance against Hinata. The act forged a deadly rivalry, with Hinata vowing to return and kill Gekkō after nine years. As part of this conflict, Hinata dispatched the demon Mirai Andou to assassinate Gekkō. Gekkō instead defeated her and bound her as his familiar through a contract.

He brandishes Spell Error, an ancient sword resembling a fencing rapier with a bell guard. Its blade appears black normally but shifts to blood-red when activating its sealing power, which nullifies magic and restrains targets. This power proves ineffective against Tenma and their Tenshi servants. The sword boasts divine origins and a 2,000-year history, bestowed upon him as the prophesied "Left Head of the Crow"—a role granting him the power to slay the witch Ramiel Lilith. He also arms himself with talismans and charms for exorcism and spellcraft.

His contract binds Mirai Andou, an upper-class lightning demon descended from the demon king Indra. He unlocks her sealed powers via a kiss on her forehead or cheek. Publicly, he labels her his "property" and treats her harshly, while privately harboring unspoken care. As student council president, he manipulates dimensional portals connected to the Holy Ground, enabling travel between worlds—a power stemming from a contract with a holy witch linked to all dimensions.

Gekkō's dynamic with Taito Kurogane evolves from mutual dislike into a fierce brotherly bond, characterized by constant bickering yet underlying loyalty. He also develops intensely concealed romantic feelings for Saitohimea, though he struggles to acknowledge them. After discovering her pact with Seraphim, he initially clashes with her but ultimately becomes her steadfast ally.