Yoo Young Doo, later legally changed to Yoo Ji Ahn and known mononymously as Jiahn, is a South Korean singer, dancer, and former member of UNIT BLACK (유닛 블랙) and SKYE (스카이; previously known as IN2IT (인투잇)). Before debuting, he attended Def Dance Skool.

He made his debut in 2017 (under his birth name) as UNIT BLACK's main vocalist with their 1st single, "Steal Your Heart". The group was the first promotional unit formed after the conclusion of the singing survival show BOYS24 (소년24). However, under their agreement, they were only active for 4 months and disbanded in August of the same year.

In October 2017, he re-debuted as IN2IT's lead vocalist, main rapper and main dancer with their 1st EP, "Carpe Diem".
Due to the COVID-19 pandemic, the members decided to enlist in their mandatory military service and, at the same time, ended their contracts with MMO Entertainment (MMO엔터테인먼트) and chose to become independent.

He was discharged in mid-2022 and founded First Entertainment alongside his group mates. In March 2023, the group rebranded under their new name, SKYE, and released their first single, "A New Beginning".

In November 2025, the group announced an indefinite suspension of activities following their last scheduled concert in December. All members will now focus on the individual work, and no further plans for them to appear as SKYE are scheduled.

(Source: MyDramaList) Edit Biography