The Midnight Romance in Hagwon Season 1 Episode 5

Director Choi Hyung-sun, the White Haired Witch, finds out that Hye-jin and Joon-ho taught the class even though there was only one student. She checks on Si-woo to see if he wants to switch academies and asks about the lecture. After hearing about the lecture, she calls Hye-jin to meet up. Meanwhile, Joon-ho asks Hye-jin not to leave the academy and stay with him for at least a year.