It's 2020. Itzy is preparing for their "Not Shy" comeback and Ryujin has been dying over Yeji's visuals. She wants to have a chance with Yeji but after hearing bad things about her from her exes, she worries. Ryujin has never had a girlfriend before. She doesn't know how to treat her girl. She never learned. But what makes it even more difficult is that she's dealing with the naughtiest girl ever to meet. Will Ryujin be able to handle the naughty girl? And will Ryujin be able to change Yeji and teach her how to love without being naughty? But first, Ryujin overcomes a disease and becomes a "monster" What will happen? Read "Naughty monster - Ryeji" to find out.