Blade of Retribution

Read manhwa Blade of Retribution / 폭력의 대가
On the day that Kendo Champion Shiho decided to help out his single mother run a Gukbap restaurant, he received news that his sister, Shiyeon, committed suicide. During the funeral, Shiho realizes that something was wrong. It wasn’t a suicide, she was murdered. In order to learn the truth and get revenge for his sister’s death, Shiho lifts up his sword once more to begin a war of his own.