U Don't Know Me - Na, Yeri

Seyun, a lithe and catty high-schooler with a mysterious past, and Yoojin, a rough-and-tumble, straight-laced Judo star, have known each other since they were children. Growing up in the same place, they're bound to have differences, and when a tragedy befalls Seyun's family, he's forced to give up his home and move away from Yoojin. A new school, new friends, and years later, Yoojin and Seyun find themselves walking vastly different paths, while struggling to maintain their friendship. But when old feelings start resurfacing, a bitter tug-of-war starts, with hearts in the balance, secrets in the closet, and twists that nobody sees coming!

(Source: Netcomics)

The series was published in English by Netcomics; physically on August 28, 2012, and digitally on January 27, 2015.