Lee Hyun Ju, known professionally as Lee Sem, is a South Korean singer, dancer, and former member of 9MUSES (나인뮤지스, also stylized as NINE MUSES). She graduated from Changwon Girls' High School and later obtained a bachelor's degree in Business Administration from Yonsei University.

Star Empire Entertainment (스타제국) and the company's CEO, Shin Ju Hak, wanted to introduce the concept of a rotating lineup with all the members being active in different fields. So, through Mnet's reality show "Children of the Empire", she made her debut in August 2010 as 9MUSES's main rapper and vocalist with their first single album, "Let's Have A Party".

However, they faced constant lineup changes as members were changed almost every year and were never able to fully develop a team chemistry. In 2014, her contract expired and by mutual agreement, she "graduated" from the group after 4 years of activities.

In December 2023, there were conversations of a possible 9MUSES comeback but nothing has materialized since then and she is unlikely to join as she is out of the entertainment industry.

(Source: MyDramaList) Edit Biography