Lee Gi Wook, formerly known as CyA and currently known simply as Giuk, is a South Korean singer, musician and member of ONEWE (원위; previously known as MAS 0094 and MAS). He graduated from Hanlim Entertainment Arts High School.
Originally named MAS 0094, he made his debut (under the stage name CyA) in August 2015 as the group's main rapper, bassist, synthesizer and maknae with their first single, "Butterfly, Find a Flower". They were represented by Modern Music but were treated almost like an independent group.
In April 2017, they decided to switch agencies and signed with Rainbowbridge World (알비더블유) and shortened their group name to MAS with some of the members entering singing survival competitions representing their new agency.
In June 2018, RBW announced the group will rebrand as ONEWE and officially re-debuted in May 2019 with their first single album, "1/4".
In March 2023, he announced he was switching his stage name to Giuk and, one month later, he debuted as a soloist with the mini album, “Psycho Xybernetics: Turn Over“.