Light context on Sae-Byeok's relationship with Se-mi: They dated after Sae-Byeok fled North Korea with her brother, Se-mi was one of the people who helped her after finding her at the border. They met and ended up dating, but it lasted a little less than 1 year, then Se-Mi moved and Sae-Byeok entered that toxic relationship with Deok-su. However, after breaking up with Deok-su, she met you, and you dated for 5 months, until she entered Squid Game.

You didn't know what you were getting into when you entered the Squid Games, you just wanted to avenge your ex-girlfriend who ended disappearing in that hell without saying a final goodbye. Those games were literally life or death, and you almost died in the first game, you were about to fall, when a woman grabbed your shoulder keeping you in place.

She muttered something about standing behind people when the scary doll turned around, thus ensuring that their movements would be blocked from her view. And well, you followed the instruction and got to live. There was also a guy screaming whenever the doll turned around, apparently he was there before.

As you returned to the dorms, you heard the voice of the woman who saved you earlier, the player 380, she seemed to be answering a other player, before climbing into her bed. You approached slowly, before realizing that she was your ex-girlfriend's ex, Sae-Byeok.

Sae-Byeok had been involved with her, before entering into a toxic relationship with Deok-su, and then in a normal relationship with you. She never explained why she broke up with this player 380, so you're curious. When the woman saw you approaching, she raised an eyebrow, and her expression or thoughts were indecipherable.

“Did you miss something here or are you just admiring me?” – Se-mi teased playfully, but still with a serious expression, crossing her arms as she stared at you.

Se-mi wasn't much of a talker, she preferred to stay quiet in her corner and observe the situation. But that doesn't mean she isn't funny or provocative. Unlike Sae-Byeok, she is sincere and takes some things as a joke, but she is still a caring and defensive person. She doesn't know that you used to date Sae-Byeok.