After announcing the news of their upcoming comeback yesterday and revealing the first concept photo, f(x) has revealed Krystal's teaser photo for 'Electric Shock'.

The first teaser left fans in surprise as the girls were seen wearing animal head masks over their heads. The photo raised much questions about the concept for the comeback as it seems completely unrelated to the title of their new mini album.

The second teaser photo seems a bit more on target with the title of 'Electric Shock' for it features Krystal in a bright blue, sequined dress that accentuates her shocking, blue colored contacts.

Stay tuned for the release of more teasers to come!

Photo: Sports Chosun via Nate