The world is not as peace as it used to be. The gate of hell have been open and monster start to poured out from the gate. Scarlett Drachen code name 'The Slayer'. Never leave anything alive when she done with the mission. She only work alone and that's her style. No one really know how 'The Slayer' looks like because in their eyes Scarlett is a nobody that got lucky with the entrance exam and a failure. She don't like to interact with other and no one has saw her taking any mission. They all thought that 'The Slayer' is a man, never a19 years old girl. She is one of the agents in 'Black Op'. This agency is place where there a chance for you to lose your life if you messed up the mission. This agency keep monsters from destroying the world. But suddenly she was asked...no...more likely being order to be in a team that have 5 boys and being their teammate. What will happen with Scarlett's live when she have to live at the same roof as those boys? Will Scarlett told them about her code name?

They were the polar opposite. Like fire and ice,oil and water,the sky and the sea. But they're force to live under the same roof. He's rich,handsome but let's not forget the important fact that he's the King of Yakuza and also a CEO for a big company. Fearless, merciless, ruthless and dangerous are the thing to describe him. He was just 18 years old when he take the title King. His parent was kill by an enemies leaving him to life with his grandmother until now. She's have to work part-time job just to pay her bills and her college fee. She didn't feel any attraction to opposite sex and she just an average college girl. She's kind,love to help other and clumsy. She was put in a orphanage because both of her parents die in car accident. Leaving her alone since kid. She didn't want to be adopted because she want to help handling the orphanage. When she was 19 she move out but still visiting the orphanage once in a while. His name is Inugami Yamato and he's 25 years old and still single. He didn't have any intention to get marry not now or ever. For him love make people weak,so he stay away from people in many occasion. Her name is Kaname Hikaru and she's 20 years old. still single and in college. Marriage was the least thing in her mind right now. Thinking about the bills,her fee and the orphanage have take all her time. From helping an old woman to marry a guy she didn't even know. See how Hikaru handle her new life. Can a marriage based on contract end with happy ending or it would end with divorced? Can Hikaru handle Yamato and vice versa?