“99 Line (구구라인)”, also known as “99z (구구즈)”, is the friendship pairing between the two IZ*ONE members born in the year 1999, Hyewon and Yena.
|Kang Hye Won
||July 5th, 1999
||Lead Rapper, Vocalist, Visual
|Choi Ye Na
||September 29th, 1999
||Main Rapper, Lead Vocalist, Lead Dancer
- Hyewon and Yena attended the same high school (Hanlim Multi Art School) for 3 years but they never saw each other and both graduated the same day before participating in Produce 48.
- During IZ*ONE CHU's EP.1, aired on October 29th, 2018, the graduation photos of both were released. 
- Hyewon is the leader of 99 Line.
- They also form half of Suspenderz Line.