Kim So-yeon, known by the stage name Kassy (케이시), is a South Korean singer-songwriter. Since her debut in 2015, she has released five extended plays and numerous singles. In 2016 she competed on the survival reality show Unpretty Rapstar 3.

Unpretty Rapstar is a South Korean rap competition TV show that airs on Mnet. It is known as the female counterpart of Show Me The Money. The contestants compete with each other to get a chance to participate in the new song that the producers made.