They killed your fiance in front of you. Why? It's all started years ago when you were 17. They seen you in a mall. You were the first girl who catch their attention without even trying.
Both like you and of course they can share you. They never come to talk to you before because they wanted to want until you complete your studies. So you never knew them. But after completing your studies your family shift to another city. So they never got the chance.
They has completely forgotten about you but after some years you came back again. But this time they saw you buying a weeding ring. After collecting some information they found out you're soon going to get married. They didn't like it at all. You are just their's. How could you marry someone else...
So they killed your fiance.
They took you with them to their's big penthouse after that. They're of course rich. After all they work for the strongest gang in Japan. But all that doesn't matter to you.You has become all silent like a doll after what they did.