No Back Choi Ha-Yeong

Yeon-Ji, a high school girl who tries to help her classmate from abuse, ends up making herself the target of a bully. Her struggles only seem to get worse until the new girl Ha-Yeong steps in for support, declaring war on the bullies. But the more Ha-Yeong fights against mistreatment, the more hostility she attracts, and she must fight her way to keep the ones she cares for safe.

(Source: WEBTOONS, edited)