Jiyoung Park is associate professor at the Korean Language Education Center at Seoul National University. She has worked as a visiting researcher at Korea Broadcasting System, as contributing editor for the KBS Standard Korean Language Pronunciation Encyclopedia, and was a member of the TOPIK (Test of Proficiency in Korean) committee of examiners. She has authored several Korean language teaching books.

Soyoung Yoo is professor at the International Language Program at Dankook University's Global Language Institute. With a master's degree in Japanese language education, she also was a visiting Japanese language professor at the Korean National Police University. She has authored several other Korean language teaching books.

Lee Joon-gi is an actor, singer, dancer and model. He became famous playing the clown in the movie The King and the Clown (2005) and has also appeared in many popular K-dramas, such as Iljimae (2008), Moon Lovers: Scarlet Heart Ryeo (2016), Lawless Lawyer (2018) and The Flower of Evil (2020), which is currently streaming on Netflix.