Gang School is a Manga/Manhwa/Manhua in (English/Raw) language, Action 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

A family that collapsed like sand castles in an instant because of their father’s suicide. I became the head of the household, responsible for my mother who had lost her mind and my sister who had to attend a school for the visually impaired. I have to transfer to the best gangster school in Busan to make my own gang for the sake of my family…