Tae-Yeon is a frail young boy with short light brown hair and big blue eyes. Due to his adorable face, he is often hugged by people around him.
He covers his hair with a light blue hat decorated with a pink ornament made up of beads and a feather. He wears a light blue overcoat atop a pale violet robe held by a light pink sash. He has bandages on both half of his arms and a yellow necklace on his neck.
Tae-Yeon takes care of Yona after she lost consciousness on Fuuga's entrance. He gives her meals and checks up on her health, which Yona finds adorable. Later, Hak states to Yona that Tae-Yeon was also an orphan like him. He adds that he was born with a frail body, and occasionally suffers from asthma attacks when he overworks himself.
During the Fire Tribe's oppression on the Wind Tribe, Tae-Yeon suffers an attack and coincidentally, the merchants who are suppose to bring his medicine has been attacked by Kan Tae-Jun's men. The following day, Tae-Yeon recovers after Han-Dae successfully got a medicine for him when he went to the herbal doctor near Fuuga.
Later, when the villagers of Fuuga are busy taking care of the wounded merchants, Tae-Yeon sees Hak off as the latter departs discreetly. Moments later, Yona appears and talks to him, saying all her gratitude for him and everyone's efforts. Tae-Yeon feels that she is also leaving and cries as he bids farewell to her. He looks back to where Hak trailed off and thinks that he can't fulfill the promise he just made with his brother earlier, which is to protect Yona.