SONAMOO members Sumin and Nahyun are believed to have departed from the group.

As a result, SONAMOO fans have been worried for some time now as TS Entertainment, the group's agency has not released any official statement since then. Also, the label is known for lawsuits against their artists such as B.A.P and SECRET, and SONAMOO has been inactive in the K-pop scene for almost two years.

SONAMOO's last release was in November 2017 the single "I (Knew It)," which they released during their Happy Box Project.

Sumin is the leader of SONAMOO and the oldest among the members. She is the first member of SONAMOO to become a trainee. She was featured in B.A.P's music videos for "Stop It," "Never Give Up," and "1004 (Angel)." Sumin also acted in episode 4 of OCN's Korean television series titled "Cheo Yong" in 2014, together with labelmate Hyosung.

Nahyun, on the other hand, is the visual and face of the group. She appeared in two music videos: SECRET's "I Do I Do," alongside fellow member Newsun, and B.A.P's "1004 (Angel)." And like Sumin, she also starred in OCN's "Cheo Yong." In addition, Nahyun was cast in "The Miracle" in 2016, "Lemon Car Video" in 2018, and "Dating Class" and "I Started Following Romance" in 2019.

SONAMOO debuted on December 29, 2014, with the extended play called "Déjà Vu." The EP peaked at number one on Gaon's weekly album chart. On July 15, 2015, the group released their second EP "Cushion." It consists of six songs including the lead single of the same title. It is said that members D.ana and Newsun participated in writing the rap part for two songs of the album: "Deep" and "Let's Make A Movie."

On June 29, 2016, SONAMOO launched their third album called "I Like U Too Much." This EP showed a different side of the group - a brighter 'girl-next-door' image - opposed to their debut concepts which the girls themselves described as "dark." On January 9, 2017, the group issued their first single album "I Think I Love U" alongside the title song of the same name.