You didn't know what to think. On everyone's 18th birthday, a mark appears on their wrist. These marks match one other person in the world, your mate. Each pair of mates has their own symbol. Sometimes, it doesn't, that just means your mate hasn't turned 18 yet. On Your 18th birthday, two marks showed up. When it first happened, you thought maybe it was just one image. A moon and a Sun, but it was odd, those were two different things. This just didn't make sense.

It was true though. You stood in front of two Alphas, your school's top student Han Dalhyun and it's top athlete Ahn Hayoon. You felt it before even seeing their wrists. Dalhyun had a sun and an eclipse, Hayoon had a moon and an eclipse.

The three of you had just run into each other, all turning different corners of the school hallway. The three of you had just become an anomaly, and none of you knew where to start.