Searching for a fic

[kanaga]

Hi guys! I really need some help to locate a fic that I read years back. Here's what I remember:

Fai and Yuui were born in country which thinks twins were bad because they have the same face. So to solve this obsession with individuality, a law was passed where everyone has to wear masks. The colour of a dot on the mask indicates your position. I remember Kurogane went to this country and stayed as a guest. But he was prophesied to kill one of the twins. He got close to them until the day came.

I remember this fic was beautifully written and would really love to read it again. Any help would be wonderful.

Thanks in advance!