His name was Mogui, and he was actually the older brother of the [Demonic Blood Fox] who died on the second trial!
Apparently, he blamed his brother's death on Tang Li Xue, Gan Aomiao, and the others since they participated in the same trial as his dead brother.
Mogui even swore in front of them and the other students that he would never forgive them for what they have done to his brother righteously, and he will teach them the harsh lesson by challenging them every time they got more than three winning streaks.
Tang Li Xue frowned deeper after she heard their story and think: 'That Mogui is really an unreasonable fox for sure! He is the same type as his little brother. He feels right to bully other people... err... another foxes weaker than him but will feel injustice when the stronger foxes bullied him. Really a worse kind of scum!'