On July 16th at 8PM KST, Lee Hyun's YouTube channel 'Hyunee Combo TV' released a video, where BTS's Jin made a surprising appearance to preview Lee Hyun's upcoming new song "The Moon in the Sea".

The two singers, who are known to be close friends, sat down in a comfortable room to share a pleasant conversation together. After Lee Hyun introduced his upcoming new song, "The Moon in the Sea", Jin commented, "The title is already so good; 'The Moon in the Sea'. The title gives the feeling where you can expect a mermaid to make a sudden appearance." In response to Jin's question on whether it will be an exciting song, Lee Hyun answered, "I would say it's a 'doo-doom-chit' kind of a beat? I tried to put my emotions into the 'doo-doom-chit' beat."

Jin paid close attention while listening to the preview of Lee Hyun's upcoming song, and stated, "I think I now know exactly what was meant by the expression 'emotions into the 'doo-doom-chit'. Hyung's voice is always a treasure." Jin continued with his detailed, genuine feedback to his fellow music label artist by poetically describing the song as "a sea filled with emotions". Jin then gave his final, general review of Lee Hyun's upcoming song by saying, "Those who seek Lee Hyun's voice and emotions, and those who seek something refreshing during the summer will probably enjoy listening to this song."

Meanwhile, "The Moon in the Sea" will be released on July 17th at 6PM on various online music sites. It is described as a trendy pop genre song. In particular, Lee Hyun personally chose the emotion-filled concept of 'the sea' and 'the moon', and participated in writing the lyrics.