C47 You are the seventh

It was not that men could not learn it, but that the Gu was an extremely cold and sinister evil being. When a man learned a Gu technique, his life would be short, so the Miao Family strictly forbade him to teach the man a Gu technique.

Mr. Gu's Gu techniques were learned secretly, his talent was extremely high, but as a man, his lifespan continued to decrease as the Gu technique increased