A homeroom teacher of Yosan Private High School has an accident, and thus a substitute comes to fill in. Han Bong-Gu is a mysterious man, and after strange occurrences the class president Ye-Rim tries to get to the bottom of this mystery.

200-year-old Min Se Yeon has managed to conceal her immortality, up until she meets Lee Jung Hoon, a social worker she saves from a traffic accident. Despite her wizened age, Se Yeon is fresh, beautiful and forever in her prime, but with immortality comes a price. Can Se Yeon and Jung Hoon defy time in the name of romance?