It is a pen of the back.
It is rough, but its concentration is not thick.
It is sold in force type. (KRW 1,500) https://beback.postype.com/post/7115111
비백의펜입니다.
거칠지만 농도가 진하지 않습니다.
포스타입에서도 판매중입니다. (1,500원) https://beback.postype.com/post/7115111

The pen of the rain bag!
I tried to name a non-backpen 2.
The two brushes had nothing in common!

비백의펜!
이름은 비백펜2로 하려 했으나
두 브러쉬의 공통점이라곤 찾아볼 수 없었다!