It Was Better Before

Four friends, Jisoo, Junseong, Yunsu, and Heechul, are active in an indie rock band. Jisoo, who plays the role of a vocalist, sings well but doesn't work hard. He does not keep practice time every day and has an impulsive personality. Looking at Jisoo who is insincere in practice, the other 3 decide to find a new vocalist. Can we find someone who sings as well as Jisoo?