He's a senior of the Northern Heavens Spiritual Academy that was squatting on the Spirit List. When Mu Chen takes his number three spot, he goes to challenge Mu Chen. But after finding out that Mu Chen was away training in the Lightning Territory, he begins to harass the other freshmen in the freshmen living area.[1]
When Mu Chen returns from his training, he's briefed on the situation by Zhou Ling. He then proceeds to defeat Mu Lun and forced him to give away his Spiritual Value points to the freshmen affected by his harassment.[2]