Lee Ru-da

Lee Ru-da is a Korean-American transfer student in Ham Dan-i's class, in his first year of high school. Because of his astonishingly pretty looks and light build, Dan-i believes he is a girl in disguise, according to web novel tropes.

He has a mysterious background and is often chased and attacked by men in suits for unknown reasons. He is possibly the heir of a Korean mafia boss, that being his mother. He is also the heir to Reed System, an international security company, son to the American owner Ian Reed. He has been trained in martial arts since he was a young child.

Appearance
Ru-da is impossibly pretty and has delicate features, so he is mistaken for a girl at the beginning. He has blonde hair and icy-blue eyes. His build is light and thin. He dress in blue and gray colours, wears hoodies a lot like Ju-in.

Personality
He seems to have an excitable and friendly nature, but has a hidden scary side. He is especially observant. He is also manipulative and tells lies to affect other's relationships. He does this with Chun-young, to make him grow distrustful of Dan-i.

Relationships
Ru-da befriends people in his class very quickly and integrates well with his classmates. But he doesn't get close to them by choice, wanting to be close to Dan-i only.

Ham Dan-i
Initially interested in Dan-i because of her blunt and unstereotypical behaviour (i.e. not being afraid of him or curious about him), he soon grows attracted to her and finds her cute and compassionate. Ru-da believes that Dan-i deserves better friends than Yeo-ryeong and the Four Heavenly Kings and attempts to create distance between them. He is always observing Dan-i.

Woo Ju-in
After he decided to work with Ju-in to prove Dan-i's innocence over the rumors, Ju-in starts calling him hyung (honorific meaning "older brother").