I Was Mistaken for the Villain is a Manga/Manhwa/Manhua in english 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

Haechan, who was so weak that he was ignored by everyone, meets a mysterious child named Miro and gains great power. However, at the same time, he discovers that the Sealing Stone, which he believed was protecting everyone, is actually the main culprit behind the world’s downfall. Though he tries to fix things on his own, people who don’t know the truth see him as a villain.