Kang Seulgi has color changing eyes, claims to be 543 years old, has the physical strengths of no human alive, and is the most beautiful person you could possibly find. Bae Irene just thinks she’s crazy. After accidently hitting Seulgi with her car one morning, Irene is thrown into a whirlwind of impossible events that she somehow starts to find more exciting than scary. Through those events, Irene starts to realize that Seulgi isn’t exactly human. So, who is Seulgi exactly? Or perhaps, the real question would be, what?