Obi is a central supporting character in Snow White with the Red Hair, serving as one of Prince Zen Wistaria's trusted aides. He is a young man of about twenty-one with short, spiky dark hair, yellow cat-like eyes, and a scar on his forehead above his left eye, often partly hidden by his fringe. His practical clothing and preference for dark colors reflect his background in stealth and nighttime movement.

His past is deliberately vague. Before joining Zen's circle, Obi lived as a solitary figure who took on dangerous and often illegal work, with strong implications of mercenary or assassination jobs. He avoided close ties and relied only on himself. After sustaining a serious injury on one mission, he disappeared from his former network. His last job was arranged by Haruka, a royal aide who wanted him to interfere with Shirayuki's presence in the palace. Instead, meeting Shirayuki and Zen changed his path: he abandoned the mission, defected, and pledged his loyalty to Zen.

In personality, Obi is easygoing, playful, and mischievous, frequently teasing those around him, yet he never crosses a line and, though he jokes, he does not lie. Beneath the lighthearted exterior, he is reserved and guarded, reluctant to speak about his past and inclined to keep an emotional distance from others. He is comfortable operating in the shadows, often active at night and known for unorthodox methods such as entering rooms through windows or balconies rather than doors.

His role in the story is that of a versatile aide and personal knight under Prince Zen, working alongside the other aides Mitsuhide Rouen and Kiki Seiran. Unlike them, Obi often operates away from the prince, carrying out independent missions as a messenger and, most notably, serving as Shirayuki's personal bodyguard during her travels. He later becomes Zen's official messenger, applying his skills to gather information, track threats, and protect those close to the prince.

Obi's key relationships are with Zen and Shirayuki. He addresses Zen as Master, and their bond combines deep loyalty, respect, and playful banter. Obi has acknowledged that he once intended to leave, but stayed because of his growing attachment to Zen. With Shirayuki, his relationship is marked by protective care and respectful nicknames, and over time he develops romantic feelings for her. He is careful not to act on those feelings, and Zen trusts him fully, confident that Obi understands where he stands. Obi also shares close camaraderie with Mitsuhide and Kiki, having been accepted into their trusted circle.

His development is a gradual move from emotional detachment toward belonging. The solitary, self-reliant loner learns to trust, rely on, and support his companions, and finds renewed purpose in watching over and protecting their futures. Through his service, he becomes an indispensable presence within the group while retaining an air of mystery about his origins.

In terms of ability, Obi is exceptionally nimble and agile, excelling in hand-to-hand combat rather than swordsmanship, though he can fluidly switch between armed and unarmed techniques. He can leap between trees with ease, land safely from great heights, and performs acrobatic feats such as standing on his hands and using his feet to disarm opponents. He carries shuriken and is also a skilled archer who uses a short bow with impressive precision. His greatest strengths are stealth, quick reflexes, adaptability, and a strategic mind honed through his former work, all of which he places in service of those he has chosen to protect.