Cassie is short for a member of the fanclub Cassiopeia, the fanclub of the Korean boy group TVXQ (and now that three of the five members left to be JYJ also JYJ)
Cassies are a big family and support their idols where they can. They are very generous and help other people, for example with donating rice in the name of TVXQ.
By the way, Cassiopeia is the biggest fanclub in the world and is in the book of world recods.
The fan colour is red.
The fanchants were so loud, Cassies are amazing!
Look at that beautiful red ocean...Cassies will always support TVXQ!