Zain is a male witch distinguished by his bird-like facial structure, backward-curving horns, and wing-like appendages extending from the back of his head. His narrow eyes and clawed hands bearing four fingers complete his unique visage. He consistently wears a white suit adorned with fur trim and laced boots throughout the series, with no significant alterations to his appearance.

Orphaned in childhood when witch hunts claimed his parents, Zain's family sent him to the human world, fearing his potent time magic would make him a target. There, he formed a deep bond with Cuff, a half-witch, half-human girl who also lost her parents to the hunts. United by shared trauma, they relied on each other for survival, traveling together to evade human persecution. Zain's early attempts to use his time magic to reverse their parents' deaths failed due to his limited power, intensifying his sense of responsibility toward Cuff.

Zain exhibits a flirtatious and free-spirited personality, openly admiring "party girls" and frequently teasing Alice about her appearance. Despite this behavior, he remains deeply devoted to Cuff and feels uncomfortable flirting in her absence. His loyalty extends broadly; he prioritizes protecting friends, demonstrated when he defied witch leader Daleth's order to destroy the Duke's logbook. Instead, he used time magic to fake its destruction, safeguarding its contents. This protective nature is further shown when he saves Cuff from a fall during a Daleth-orchestrated circus performance.

His primary ability is time magic, enabling him to stop time and create portals for temporal travel. This power proves instrumental: he facilitated the Duke's journey to confront the witch Sade, enabled the final battle against her by creating stable portals, and later revived Sade after her defeat. Zain can also transform into a white crow, using this skill for flight and discreet movement. Sade is noted as the only witch powerful enough to counteract or break his time magic.

Recruited by its ringmaster, Zain and Cuff join Circus Gemini, forming a found family with the performers. While working there, Daleth repeatedly targets Zain, attempting to exploit his magic. This pressure led him to consider abandoning Cuff for her safety, but he ultimately confessed his love instead. Their relationship evolved into a romantic partnership, and they later moved into an apartment together while continuing circus work.

In the series' conclusion, Zain's magic enables the confrontation that breaks the Duke's curse. He attends the Duke and Alice's wedding with Cuff, maintaining his circus employment. His character arc resolves with stability in his personal life and magical pursuits, having honed his abilities at a wizarding school earlier in the story.