윤종신
Some of the songs in the album were composed and written by IU herself, with help from artists like Lee Juck, Kim Hyeon-cheol, Yoon Sang, Yoon Jong-shin, , and Corinne Bailey Rae. Her agency, LOEN Entertainment stated, "The album has been worked on for a long time, and the exclusive content included in the special limited edition will enable fans to better understand the album production process. It's a special gift from IU to those fans who have waited a long time."