Former f(x) member Sulli has released her debut single four years since leaving the K-pop outfit. 

Launched via SM Entertainment, the singer dropped "Goblin" on June 29, a mellow pop track wherein the narrator candidly talks about how she thinks others perceive her. 

On the same day, Sulli also unveiled the music video for the titular track. The accompanying visual sees her take on different personas as she breathes life to a protagonist with a dissociative disorder.

"This is a story about a person with a dissociative order. She is with herself and with three other personalities," the video stated in the intro, followed by a minute-long dialogue with a person -- perhaps a psychiatrist or a therapist -- asking about her condition. 

The song and the video have both been receiving positive responses from the audience as it raises awareness about mental health. 

A YouTube user (with username "nutahk ame") commented: "This is not just a concept. This is a movement. Idols talking openly about mental health is a must. I know this is not the first time but I hope more and more artists can get through to the Korean public about mental health issues."

"Goblin" also comes with two more tracks completing the single album -- "On The Moon" and "Dorothy." In all three songs, Sulli has participated in both lyric-writing and composing. 

To commemorate her debut solo material's release, she held a special stage titled "Peaches Go!blin."

Though her first stint in the Korean entertainment was as a child actress, she was launched as a K-pop idol in 2009 as part of f(x), together with Victoria, Luna, Amber, and Krystal. They are most notable for the songs "Electric Shock," "La Cha Ta," and "Hot Summer."

She left the group in 2015 to focus on her acting career. In 2017, she landed a starring role in the film "Real," alongside Kim Soo Hyun.

In November last year, she was featured in R&B singer-songwriter Dean's single "Dayfly."

Prior to her leaving f(x), Sulli was already on hiatus since July 2014 after facing malicious comments and rumors.