The Rapper Line is one of the two MAMAMOO sub-unit made up of Hwasa and Moonbyul; it is also the name of the friendship pairing between the two. They are considered to be the most "hip" pairing and both are the main rappers of MAMAMOO.
Their other name "HwaByul" comes from the combination of Hwasa and Moonbyul's names.
- Moonbyul is older than Hwasa by three years.
- Moonbyul is the tallest of MAMAMOO while Hwasa's the third tallest of the group.
- Moonbyul was born in Bucheon, South Korea, but Hwasa's born is Jeonju, Jeollabuk-do, South Korea.
- Moonbyul has four tattoos while Hwasa has five.
- Hwasa has two older sisters while Moonbyul has two younger sisters.
- Moonbyul has three pets while Hwasa has none.
- Their blood types are B.
- Both are part of the Jji-Jil crew.
- Both have their own Instagram accounts.
- Both have sisters.
- Both are songwriters.