Sapphire. That's what the police and FBI called the best girl in Seoul at killing people. But her killing usually based on the fact that the victim did something bad to the citizens without they knowing. What they don't know is YOU are Sapphire and you're not working alone since your 'brothers', BtoB, are helping you in their own ways. The one who help you the most is Sung Jae since he's your trusty partner.

But on one of your tasks, you got shot and some guy helped you. What if you realized that that guy is not what you think he is? And what will happen if your past that you used to believe is a whole lie?

Cast:

You (Name: Lee ___ ___, Codename: Sapphire)

- A sweet girl, but when she kills, she gives no mercy

- Parents died because of accident (what she was told by the company)

- Speciality: almost all you can imagine. Best in guns and combat

- She only remember her memories from she was 8 years old.

- Sungjae is her partner

- Working under Cube company

- Always haunted by a weird dream (will be revealed)

Kevin Woo

- A member of U-KISS

- Working under NH Company

- Other facts will be revealed

Yook Sungjae (Codename: Citron)

- Your partner

- Also working for Cube company

- Speciality: Tech (he's the one who breached the building's security systems)

- Have a little feeling in you

- Member of BtoB

BtoB

- Your friends

- Minor character (but being revealed first ^^")

U-KISS

-Working under NH Company

Cube Company

- Where you and BtoB working to

- Has a little secret that you and BtoB musn't know

NH Company

- Where U-KISS working to

- Also has a secret that U-KISS musn't know either