Second Prince of Clarines, Zen Wistaria stands approximately 176 cm tall, distinguished by silver-white hair and blue eyes. He typically wears a blue uniform with a sword at his waist, adding a white cape for formal duties or choosing simpler dark attire informally. A distinctive royal blue glove consistently covers his left palm and middle finger.

Zen presents an easygoing, kind, and approachable demeanor, valuing respect and equality for all regardless of status, which inspires deep loyalty. Though he dislikes formalities, he shoulders his royal responsibilities seriously, compensating for personal excursions with intense work. He harbors a strong aversion to daylight solitude and struggles with perfumes and colds. Threats to loved ones trigger formidable seriousness and fierce protectiveness. Childhood exposure to controlled poisons granted significant immunity, later neutralizing an assassination attempt via poisoned apple.

His early life was marked by isolation and political pressure. At thirteen, during a rebellious phase, his elder brother Crown Prince Izana assigned Mitsuhide as his aide. Zen initially resisted, behaving coldly until confronted about his hurtful conduct. Secretly during this time, he befriended castle archer Atri, who later revealed himself as a spy for a faction seeking revenge against Izana. Atri's betrayal culminated in a violent confrontation outside the castle; Mitsuhide fatally wounded Atri to protect Zen. As Atri died, lamenting Zen's royal status, Zen was emotionally devastated. This event forged his resolve to earn genuine loyalty and forge connections beyond his title.

He first encountered Shirayuki after injuring himself vaulting a forest wall. Suspicious, he accused her of potential poisoning, prompting her to demonstrate her medicine's safety on herself. Her integrity shifted his perspective, sparking a bond over shared values. When Prince Raj of Tanbarun poisoned him to coerce Shirayuki into becoming a concubine, Zen leveraged his royal status to intimidate Raj into relinquishing his pursuit, facilitating her move to Clarines.

Romantic feelings for Shirayuki grew, culminating in a confession of love and a kiss. Their relationship thrives on mutual support: Shirayuki inspires his dedication to princely duties, while he repeatedly rescues her from danger. He intends marriage, though their differing statuses pose challenges. Core relationships include irreplaceable friends and confidants Mitsuhide and Kiki, his aides for over five years. He later integrated former outlaw Obi into his service after testing his loyalty, eventually knighting him personally despite Obi's lack of formal training.

His familial interactions are complex. He respects his mother Queen Haruto's cheerful cunning but maintains a strained, formal dynamic with Izana due to differing governance approaches and Izana's initial interference with Shirayuki. Tensions eased somewhat after Izana acknowledged Shirayuki's capabilities. Zen demonstrates perceptiveness, distinguishing identical twins and recalling specific details about acquaintances.

His journey reflects a path from isolation to forging authentic bonds, balancing princely duties with personal integrity, and navigating love amidst political expectations.