His agent is Alpha (no doubt about it).
Alpha is a company in Wu Zongxian. Brother Xian doesn't attach importance to brokerage work, so the company is not very big, so now he simply gives it to a friend. Before Jay became famous, Alfa was definitely a small company, and now it is a "medium" company, but Alfa is only basically able to release movies (compared with the weekly release momentum), so some albums have to be released by Sony.
Warner is a large media company. What's wrong with going to a concert in Jay Chou?