Yu Dayun

Dayun is Ijin's younger sister. 10 years after Yu Ijin died in a plane crash along with their parents, Dayun and her grandfather received a phone call from him stating he was still alive and so he came back to his hometown in South Korea to live with them. During those 10 years he was trained as a soldier and was encouraged by his superiors to go back home and "live a normal life". Before he came, Dayun was being severly bullied for 2 years by girls of her class but Ijin solved that issue when he came back.