Four long years since his last comeback, and Bobby Kim released his fourth EP, Mirror, to the public on October 22. Through his release, the singer revealed he feels like he is starting fresh again. 

"I feel as if I have become a nervous rookie singer again," he said of the new album.

For his title song, "Apology," Bobby Kim enlisted in the help of his close friend and well-known musical talent Lee Juck, wrote the song's lyrics.

Lee Juck, in turn, supported his friend's comeback with a video message. "As a writer I found comfort through the song and became thoughtful about the song, "Apology," and its meaning," he said. "The title signifies a story about a couple who dated for a long time and how the guy is apologetic to the girl."

Along, with the help of Lee Juck, Bobby Kim's father, Kim Young Geun, also participated in the comeback through the music video. His father can be seen playing the trumpet in the background of the video.

The music video also stars actress Yoo Da-In as the female lead. It shows a girl and a guy reminiscing about the past of their relationship when it was filled with happy memories.

In addition, Kang Hye Jung, Tablo's wife, also participated in the album by writing the lyrics to the song "Good Thing."

Many fans can look forward to his comeback stages and performances through his new album.