Following a series of photo and video teasers, Won't Forget You and the lead single "Hush" were simultaneously released.

[3] After eleven years with Woollim Entertainment, Kim decided to not renew his contract with the agency upon its expiration on March 6, 2021.

[4] On March 20, 2021, the company posted an image of a stamped envelope and a postcard adorned with purple flowers, announcing Won't Forget You as Kim's final album with the label.

[7] In the third batch, Kim is seen donning a blue jacket with yellow pants and wearing a navy suit while lying on the ground.

[8] The final bundle presented him clothed in a white suit with a patterned shirt, as well as a photo of him under red lights staring at the viewer.