4 Walls is the fourth studio album by South Korea-based girl group f(x), released by SM Entertainment and Genie Music on October 27, 2015. A dominant electropop and synthpop record that incorporates various genres, such as house, EDM and UK garage, 4 Walls was composed by several production teams and songwriters, namely LDN Noise, The Stereotypes, Kenzie, Ryan S. Jhun, Makeba Riddick, Carly Rae Jepsen, among others, with Lee Soo-man served as the executive producer of the release. It marked f(x)'s first major release since Red Light in July 2014, and subsequently the group's first and currently the only major release as a quartet since the departure of former member Sulli in August 2015.

Min Hee-jin (Korean: 민희진) is a South Korean art director and graphic designer. She is the current CEO of ADOR, a subsidiary of entertainment company Hybe Corporation, where she previously served as chief brand officer. She was formerly a creative director at SM Entertainment, where she was responsible for the branding of groups such as Girls' Generation, Shinee, f(x), Exo, and Red Velvet.