Lee Su Ji is a South Korean actress and singer. She is a former member of the girl group The Ark (2015-2016) from Music K Entertainment. She was previously known as Halla but now uses her real name, Su Ji. She participated in the survival show, The Unit, and managed to secure the 9th spot, leading her to debut as UNI.T. She was also a member of the cast of Real Girls Project - The Watch drama online for free.