f(x)'s Sulli updated fans with her new, longer hairstyle.

Sulli shared on me2day on the 30th, "My hair is long....," along with the photo above.

Fans were left shocked by her transformation and guessed that she might be wearing extensions.

They commented, "Is that your real hair?", "How can your hair grow so fast?", and "You look pretty with short or long hair".

Sulli recently wrapped up the SBS drama 'To the Beautiful You', and her short hairstyle in the drama is reported to have caused a trend.

Do you prefer Sulli with long or short hair?