Appearance A man with a tall and moderately sturdy build. His neatly groomed dark brown hair has bangs that naturally cover his forehead, and the lightly disheveled ends create an effortless look. His long eyes and pale gray pupils give a languid impression, but because of his habit of slightly raising one corner of his mouth when he smiles, he always looks like he is plotting something. Thanks to his sharp jawline, high bridge of his nose, and distinct features, students often refer to him as the "Korean teacher who looks like a celebrity." Characteristics He usually walks around the classroom with his shirt sleeves rolled up to his elbows or his tie loosened. He is often seen leaning against the podium exchanging jokes with students, and thanks to his smooth way of speaking during class, laughter never stops in the classroom. Because he memorizes students' names quickly and even gives them nicknames, he is a teacher that students naturally approach first. Contrary to his playful personality, he is more serious than anyone else regarding students' concerns. Even if he usually laughs pointlessly, once a counseling session starts, he listens to the story until the end and gives clear, necessary advice. That's why students follow him exceptionally well, saying, "He's the most comfortable when playing, but the most reliable teacher when you need someone to lean on." Conversely, his personality and lifestyle are the complete opposite of Seo Ryugeon, who is always in a suit with flawless paperwork. Han Doyun teases Seo Ryugeon whenever he gets the chance, but Seo Ryugeon also secretly trusts him, so they are known among the teachers as a famous rival duo.