L.E.J, short for Lucie, Élisa and Juliette, sometimes Elijay, are three young French students and vocalists who condensed numerous top songs from the summer of 2015 into a mashup performance. Their music is based on classical and world music, described by MTV reviewer Joseph Lamour as "eclectic". Their song mashup Summer 2015 had millions of plays on YouTube as of August 2015. According to Seventeen magazine, the three vocalists were best friends from childhood, and have been performing together since 2012. Reviewer Hannah Orenstein described their sound as "pared-down but strong." Juliette plays the cello.
All three women were born in 1993: Lebrun on November 21, Paris on August 26, and Saumagne on September 3. They were childhood friends from Saint Denis. Juliette studied cello at the Conservatoire de Saint-Denis. In 2013, they competed in the Tyro competition, performing for a large audience, and won; at that point, according to one source, the group did not yet have a name. To a large extent, the group connected with listeners through social networks. Elisa said in an interview that the women would not have worn their pajamas when recording Summer 2015 if they had known that the video would have gone viral. There are plans to record an album in 2016, in French, written by the three of them, and the women feel tremendous pressure to not disappoint anybody; Elisa said that recording this album would be the group's greatest challenge.