Kim Won Joo is a South Korean singer and member of the duo 2F. He graduated from Honam High School and later attended Inha University but is on a leave of absence from the Mechanical Engineering program.
He was supposed to debut in 2008 as part of the third generation of the group 4Men alongside Kim Young Jae and Shin Yong Jae, but he did not participate in the recording of their 1st EP album, "First Kiss". He officially debuted in 2009 when the group sang the OST for the SBS drama "Family’s Honor". During his time as a member of 4Men, he had a light and soft tone, and he was assigned high-pitched parts in a lot of songs, something he was not very confident in as his high tones were not as strong as the other members.
He began participating in musicals around 2013 to improve his skills, but many considered him the weakest 4Men member. In 2019, it was announced that both he and Shin Yong Jae had left MAJOR9 after their exclusive contracts expired. A few months later, both decided to form the vocal duo 2F. He is quite an introvert, so he leaves the majority of promotions and TV appearances to Shin Yong Jae.
(Source: Korean = NamuWiki || Translation = MyDramaList)