In Lost, Sun and Jin Kwon’s unborn daughter was named Ji Yeon. Sun gives birth to her after returning to the mainland.
Sun becomes pregnant while the survivors are on the island, and the pregnancy creates uncertainty because the island appears dangerous for expectant mothers. Sun eventually leaves the island with a group of survivors, while Jin is believed to have died in the freighter explosion.
Ji Yeon is raised by Sun after the events on the island. The name is revealed in episodes that follow Sun’s life away from the island and her continuing search for Jin. Ji Yeon should not be confused with Aaron Littleton, Claire’s son, or Alex Rousseau, another important child in the series.