I get it now... so... like.... if u change the past there will be consequences?? Like butterfly Effect??
She's not trying to change the past, she just want to save the guy, but that incident still exist. A person probably just get taken randomly as a hostage and got killed, but since Lee-Yul wasn't there, another took his place. Of course this is coincidental but because of her action saving him, another died in his place.
Ohohoho Emel u are sooo fuck hehe