Brave Shimin is a Manga/Manhwa/Manhua in english language, manhwa series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Seo Shimin is a wild hapkido practitioner who conquered the whole country while in school. Seven years later, her metamorphosis showed up as a shady part-time teacher at her high school. Currently, her interest is not for the benefit of the ‘students’, but only the ‘promotion of a full-time teacher.’ However, a vicious student Han Soo Kang appeared in front of her, and Shimin became his targets. Will the dream of Seo Shimin who just wanted to become a true teacher come true?