"Beauty in the Prosperous Age is Guan Jiuhai" is a classic quotation that Guan Jiuhai himself said in the cross talk performance of Deyun Society.
The whole sentence is: "Six branches are based on nine seas, and Shi Sheng Meiyan is based on nine seas". Later, netizens invented the phrase "Shi Sheng Meiyan is based on nine seas, and Deyun Huakui is based on nine seas".