Season 4, Episode 7:

Ji Yeon

On the Island, Sun begins to doubt the freighter crew's motives of rescuing the survivors. She and Jin decide to join Locke's camp. Juliet discovers this, and tries vainly to convince Sun, who does not trust her, that she needs to leave the Island or she will die. Juliet tells Jin about Sun's affair with Jae Lee, and he angrily returns to the beach. After a heart-to-heart with Bernard, Jin forgives Sun, and accepts that the baby is his. The two decide to remain with Jack.

On the freighter, the captive Sayid and Desmond are slipped a note telling them not to trust the captain. As they are taken to see Captain Gault, Regina wraps herself in chains and jumps overboard. Gault refuses to do anything about it, saying that many of his crew are suffering from a heightened case of cabin fever due to their proximity to the Island. He explains that someone on board has sabotaged the engines, and that he was hired by Charles Widmore to retrieve Ben, who he accuses of having faked the recovered wreckage of Oceanic 815. Sayid and Desmond meet a deckhand named "Kevin Johnson", who is actually Michael.

Off the Island, a heavily pregnant Sun realizes she is going into labor and calls an ambulance. Jin buys a stuffed panda as a birth present, and rushes to make it to the hospital on time. Sun gives birth to a girl named Ji Yeon. It is revealed that while Sun's scenes are flashfowards, Jin's are flashbacks to an errand he ran for Mr. Paik years before the crash for the birth of an ambassador's grandson. Hurley visits Sun, and the two of them visit Jin's grave together.

Tropes in this episode include:

• Bait-and-Switch: The episode is set up so viewers assume Jin's scenes are him trying to get a present for Sun before their baby is born. His final flash reveals that their scenes cover two separate events in different time periods.
• The Bus Came Back: Michael returns as a janitor on board the freighter under the alias "Kevin Johnson".
• Continuity Nod:
  • In a flashforward, Sun watches a Korean dubbed version of Nikki's guest appearance on ''Exposé''.
  • Jin mentions that Sawyer has been teaching him English.
• Downer Ending: The episode ends on the revelation that Jin doesn't make it off the Island, and is presumed dead.
• Emerging from the Shadows: The doctor calls for Kevin to clean up a blood stain on the wall. He slowly walks down the corridor to reveal he's actually Michael.
• Foreshadowing:
  • Jin behaves much more like his Jerkass Season 1 self in his off-Island scenes, threatening to hunt down and kill the man who steals his taxi, hinting that they are actually flashbacks to before the crash.
  • When Jin goes to the toy store a second time after losing the first panda, the owner recommends a dragon, saying it's good luck for the Year of the Dragon. At the time of airing, the most recent Year of the Dragon was February 2000 - January 2001, which hints that it was a flashback.
  • The fact that Jin is so insistent on getting a panda to begin with, which would seem like an odd thing to be concerned about if he was racing to be on time for Sun giving birth.
• Imperiled in Pregnancy: Juliet explains to Sun why she needs to get off the island now, regardless of whether or not the boat is friendly.
  "In about three weeks, you'll be in an almost constant state of nausea. A week after that, you will experience shortness of breath that won't go away. A week after that, you will lose consciousness and slip into a coma. And then, Sun, you will die. And when your heart stops beating... so will the baby's. And that, Sun, is why it is my business, because you are my patient. If you go... you will die. And your baby will never be born."
• Internal Reveal:
  • Juliet tells Jin that Sun had an affair in an attempt to stop them from joining Locke's group.
  • Bernard reveals to Jin that Rose has cancer that's being kept at bay by the Island.
  • Captain Gault tells Sayid and Desmond that the boat is owned by Charles Widmore.
• Panicky Expectant Father: Subverted when it's revealed that Jin's rushing around trying to buy a baby gift is actually him running an errand for Sun's father.
• The Reveal: Sun is confirmed as the last of the Oceanic 6. There's also the reveal at the end of the episode that Jin and Sun's off-island scenes show two different time periods. Ben's man on the frieghter is Michael under a false name.
• Rushed Inverted Reading: Lapidus notices that the book Regina is reading is upside down. In this case, however, it's a sign that she's starting to suffer from the cabin fever that's slowly affecting the freighter crew.
• Simultaneous Arcs: Subverted with Jin and Sun's flashes. It's initially made to seem like they're taking place at the same time until The Reveal.
• Wham Line: Jin saying "I've only been married two months" revealing that his storyline is actually a flashback to just after he and Sun got married.
• Wham Shot: "Kevin Johnson" walks towards the camera and reveals he's actually Michael.
• You Have to Believe Me!: Juliet desperately tries to convince Sun both she and her unborn child will perish if they remain on the island. Sun refuses to listen and along with Jin, begin to head for Locke’s camp at the Barracks. Juliet has to take drastic action to stop this.