Obanai is a 21-year-old young man of short stature and a pale complexion. He has straight-edged black hair of varying lengths, the longest reaching down to his shoulders and the shortest stopping at his cheekbones, which he wears down with two shorter strands hanging between his eyes. His Demon Slayer Mark appeared as snake-like patterns stretching from his left arm up to his chest. Along with enhancing his natural agility, power and endurance, it allowed him to turn his Nichirin blade red.