Sebek is a tall muscular boy with fair skin. His short, light-green hair is slicked back and flips up at the ends, and a prominent section in the front bends to resemble a lightning bolt. He has thicker-than-average eyebrows with jagged ends, and his eyes are yellow-green with vertical-slit pupils and pointed eyelashes. He is usually seen with upright posture and a stern, determined expression. When his mouth is open, sharp fangs are visible.