Yu Sheng was diagnosed with a congenital left-hand deficiency at birth and accompanied by mild mental retardation, and his father has since bid farewell to the boxing ring to live with him. Because Yu Sheng was bullied, his father taught him boxing. When Yu Sheng grew up, he disregarded his father's opposition to the boxing of the professional competition and became famous, but he was suspended indefinitely because of irregularities on the court. Yu Sheng found his father close to blindness. In order to treat his father, he went to the boxing bar and was beaten to earn money.