Mikuburai is a young man who seems to arrive in pieces: first the measured scrape of a poleaxe ferrule, then a forest-green mantle, then the broad, riveted silhouette beneath it. His armor is old-fashioned plate, painstakingly repaired with Japanese lamellar plates and bright, visible rivets. Its surfaces are not polished smooth; hammer dimples, blackened seams, and shallow etched lines catch the light like ripples in a forge trough. He walks with a steady, heel-first tread, but can pivot abruptly on the balls of his feet. His square jaw and slightly crowded front teeth show whenever he bites into food or laughs. Unexpectedly for a knight, he keeps a tiny folded paper crane tucked inside his helmet and checks it with his thumb before a fight.

Mikuburai is decisive when another person is in danger but hesitant when choosing what he wants for himself. He is proud of his strength and deeply uncomfortable with praise. In a workshop he is patient, exacting, and willing to admit a mistake; in a crisis he becomes blunt and difficult to redirect. Among friends he is unexpectedly playful, but a reminder of his mentor's death makes him withdraw into grim duty.

Mikuburai Takashi McBrian is the son of an Irish line that crossed oceans and a Japanese family of metalworkers. His ancestor Seán mac Briain left Ireland during the Great Famine in 1847, carrying the battered plate of the old Order of the Emerald Cross, its sacred poleaxe, and a reliquary of Saint Patrick. In Nagasaki, Seán was taken in by a metalworking household and married Aiko Takamura, whose knowledge of unusual alloys changed how the order's armor could be repaired. Generations later, the old vows survived less as a commandment than as a family argument: what is worth protecting, and who gets to decide? At sixteen, Mikuburai apprenticed under his mother, learning to hear flaws in metal by striking it and listening. During a demon raid on a coastal settlement, he froze when a frightened child clung to his leg. His mentor, an aging smith, died holding a gate long enough for the villagers to escape. Mikuburai took up the repaired armor and poleaxe afterward, adopting the name Cavaleiro Verde as a promise to be the person who moves when others cannot. Now he fights demons while trying to keep his family's forge open, care for his widowed mother, and learn whether the relic's old reputation is faith, history, or simply a burden passed down. His childhood friend Shiori, a courier who brings news from the threatened coast, thinks he is wasting himself on a legend; he trusts her judgment more than he admits.