Aiko begins her existence as Hans, a 13th-century crusader soldier betrayed and left to die during the holy wars, his final oath echoing a vengeful rebirth as a fallen angel. Resurrected centuries later as a woman, she ascends as a formidable military strategist, leveraging her tactical brilliance to dismantle global religious institutions and impose a secular world order—a crusade fueled by fragmented, haunting memories of her martyrdom. These echoes of her past propel her through time, thrusting her into medieval battlegrounds to thwart apocalyptic threats rooted in her former life.

Her temporal missions pit her against a demonic entity that weaponizes her unresolved bond with Daisuke, a figure entwined with both her historical anguish and fractured heart. Navigating dual identities—the disciplined commander and the tormented soul—Aiko maneuvers through eras, her strategies clashing against the machinations of fate. Her physical guise—brown hair, grey eyes—belies the ancient fury within, while her modern facade as a St. Michaela Academy student thinly veils her relentless drive to reshape history.

Each intervention in the past ripples into her engineered future, entangling her in a paradox where altering her own betrayal risks unraveling the secular empire she built. This duality fractures her existence: one thread wages war on faith, another seeks redemption for the lives lost across timelines. Her confrontations with iterations of herself and others blur the lines between perpetrator and savior, as she sacrifices fragments of her sanity to mend a legacy stained by vengeance and hubris.

The cycle persists—a collision of free will and predestination, where every choice echoes the angel’s oath and the soldier’s wrath, binding her to an eternal reckoning with identity, power, and the cost of rewriting destiny.