Block B's Zico's solo songs hold a poignant secret.

Freestyle Town, the record label home to several Korean hip-hop artists including San E and Sool J, revealed some secrets about Zico's solo songs. The hip-hop outlet shared that the reason why Zico's hip-hop solo songs were all four minute and sixteen seconds long is because the songs are tributes to the victims of the Sewol Ferry tragedy, which occurred on April 16, 2014.

Zico (Woo Ji Ho,) a member of Block B, released his solo song "Tough Cookie" in Nov. 2014 and "Well Done" on Feb. 12. At the time of their release, Zico posted messages on Twitter that highlighted the timing of each song.

On November 3, Zico wrote, "The full-length version of "Tough Cookie" has a run time of 4 minutes and 16 seconds."

완곡버전의 터프쿠키는 러닝타임 4분16초짜리 곡입니다

— ZICO (@ZICO92) November 3, 2014

On February 12, Zico wrote a nearly identical tweet, "My new single 'Well Done' has a running time of 4 minutes 16 seconds."

새싱글 Welldone 의 러닝타임은 4분 16초 입니다. — ZICO (@ZICO92) February 12, 2015

In between the release of the two songs, Zico tweeted a message about the Sewol Ferry accident on the last day of 2014, once again highlighting the number "4.16."

"Even if time [he used the word sewol, which is translated as "time" or "years" rather than the usual term shigan, "time"] passes, That Sewol let's not forget. Don't forget never forget 4.16," the idol wrote, along with sharing a picture of the yellow ribbon that was used to memorialize the tragedy.

세월이 지나도 그 세월만은 잊지않도록 Don't forget never forget 4.16 pic.twitter.com/O6bmt4imIu

— ZICO (@ZICO92) December 31, 2014

Although Zico has highlighted the time of the songs on Twitter, he has never directly made the connection in an interview.

Along with the songs, Zico has a close relationship with the victims of the Sewol Ferry incident. He commemorated one fan by attending her funeral, and dedicating a rap to her at a concert last May. The concert took place on the day of her birthday, and her father revealed in an interview with Channel A that he had promised to let her go prior to the tragedy.