What are emotions?

This Yeo-ju : Carat University freshman (20 years old) : Famous as Lee Ji-hoon's younger brother : Woosung Omega Kwon Soon-young : Carat University sophomore (21 years old) : Carat University convenience store part-timer : Lee Ji-hoon's friend : Woosung Alpha Lee Ji-hoon : Carat University sophomore (21 years old) : Applied Music major : Lee Yeo-ju's older brother and Kwon Soon-young's friend : Woosung Alpha Choi Seung-chul : Carat University freshman (20 years old) : Lee Yeo-ju's friend