Whatever it is for that story.
Beta is an slim shaped guy with brown hair and light blue eyes. He has his hair into a ponytail and his skin color is kind of lightish. He has a large deep cut on his back that he rather hides and never shows it due to his clothing. HIs clothing consists of a long black hoodie with a white T-Shirt undershirt. He has black jeans on that are kind of slim on him, but easy to be flexible in and black and white converse sneakers.
Beta has a very passive, calm and seemingly apathetic attitude. Along with his passive demeanor, Oreki seems to always "conserve energy" and never exerts effort on anything unless absolutely necessary; thus coming off as lazy. His power is perfect for his personality since he barely uses energy to use his power. Also, because of his attitude, Beta talks little and rarely shouts or gets angry, though he does appear to get irritated often.