Hissing (2004)

Blurb:
Da-Eh, an aspiring manhwa artist who lives with her father an little brother, comes across Sun-Nam, a softie whose ultimate goal is simply to become a “tough guy.” Whenever these two meet, trouble follows. Meanwhile, Ta-Jun, the hottest guy in town, finds himself drawn to the one girl that his killer smile doesn’t work on — Da-Eh. With their complicated family history weighing heavily on their shoulders, watch how these three teenagers find their way out into the world!

Source: www.anisearch.com/manga/729