Mr. Magical Girl 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

202X. In the back alleys of Seoul, South Korea… He looked down at the heroes under his feet—the heroes who adorned themselves in a variety of colorful clothes, as if they were K-pop idols on TV. Those heroes? They were crawling beneath him, their gaudy outfits smeared with dirt. That was the true nature of being a hero. He hoped the individuals before him learned that lesson well. It was time to ensure they never forgot it. As a magical girl, he swung his hammer down. This is a bright story. The story of a man reclaiming his light.