Seong-je is described as being playful, not taking things too seriously, and having an air of arrogance and attitude around him. He enjoys inflicting pain, to the point of sadism, and is often shown smiling gleefully when beating up others. Seong-je has dark curtain cut hair that is layered, and is of medium length (bangs reaching his eyebrows). He has pale skin, is slim, tall, and wears half-rimmed glasses. Seong-je has incredible physical strength, durability, and speed. He primarily uses Boxing-like punches (in-fighter-out-fighter hybrid), and uses grounded kicks efficiently, rather than flashy ones. He can clinch, grapple minimally, and his style is influenced by street MMA