Former Girls' Generation's member Jessica congratulated her sister, f(x)'s Krystal, on her birthday.

On October 24, Jessica posted on her Weibo, "Happy birthday~ I love you a lot. Happy birthday my dearest sis. There was a time when I used to be... taller than you!" along with a picture.

In the picture, Jessica and Krystal are young children riding a helicopter ride at an amusement park.

Jessica left Girls' Generation on September 30 and is now focusing on her fashion business work.