His fighting style is based on Shaolin kung fu, a Chinese martial art.
Virtua Fighter 4
During the ancient days in China, one emperor declared that all powerful martial art techniques shall be banned. This decree was done with the intention of ensuring that no one shall possess a more powerful technique than the emperor himself. The emperor also saw to the deaths of anyone who was capable of powerful techniques. He created a clan whose sole duty is to capture and kill anyone with such powerful capabilities. Ko'en-Ken was one such skill that was banned by the emperor during that age. While no emperor exists in modern China, the clan that was created still exists. When informed of Ko'en-ken's appearance in the world tournament, they decided to send Lei to stop Lau from using Ko'en-Ken. Lei accepted this mission as he saw it as a chance to test his skills against the mighty Ko'en-Ken. However, Lei intends to kill Lau after he has learned Ko'en-Ken from Lau.(taken from US/European manual of Virtua Fighter 4)
Virtua Fighter 5
Lei-Fei admired the amazing power of Lau Chan's Ko'en-Ken style and he approached him after the tournament and asked to be his student. Soon Lei-Fei grew impatient with the aging fighter and he attacked him; Lau was unable to fight back and he withdrew and disappeared. Lei-Fei was angry that he failed to learn the coveted technique and he decided his only chance of winning the next tournament was to become stronger than any opponent.(taken from US/European manual of Virtua Fighter 5)