My Magician Senior is a Manga/Manhwa/Manhua in english language, SUGGESTIVE 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

This is a world where science and magic coexist. Here, some people pursue powerful magic, while others learn eternal truths. The protagonist, Blair, a mathematician who came from a different world, with left-handed magic and right-handed science, opens the door to a new world! Academic Dean? Supreme Witch? Senior Killer Brother? As an adult, I want it all!