[Pictures] Comeback concept photos of Sulli & Amber revealed~

New concept photos of f(x)'s Amber and Sulli have been revealed.

It seems that the girls are going to show us some gloomy side of themselves in their upcoming album,the girls have been showing us much happiness during the promotional activites of "Chu".Fans were surprised with Sulli's hair colour and they responded by saying that Sulli looks gorgeous in these photos.

Their new album is set to be released on 4th May!!